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Hibernate example source code file (Dialect.java)
This example Hibernate source code file (Dialect.java) is included in the DevDaily.com
"Java Source Code
Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.
The Hibernate Dialect.java source code
/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2010, Red Hat Inc. or third-party contributors as
* indicated by the @author tags or express copyright attribution
* statements applied by the authors. All third-party contributions are
* distributed under license by Red Hat Inc.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*/
package org.hibernate.dialect;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Blob;
import java.sql.CallableStatement;
import java.sql.Clob;
import java.sql.NClob;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
import org.hibernate.HibernateException;
import org.hibernate.engine.spi.SessionImplementor;
import org.hibernate.internal.CoreMessageLogger;
import org.hibernate.LockMode;
import org.hibernate.LockOptions;
import org.hibernate.MappingException;
import org.hibernate.cfg.Environment;
import org.hibernate.dialect.function.CastFunction;
import org.hibernate.dialect.function.SQLFunction;
import org.hibernate.dialect.function.SQLFunctionTemplate;
import org.hibernate.dialect.function.StandardAnsiSqlAggregationFunctions;
import org.hibernate.dialect.function.StandardSQLFunction;
import org.hibernate.dialect.lock.LockingStrategy;
import org.hibernate.dialect.lock.OptimisticForceIncrementLockingStrategy;
import org.hibernate.dialect.lock.OptimisticLockingStrategy;
import org.hibernate.dialect.lock.PessimisticForceIncrementLockingStrategy;
import org.hibernate.dialect.lock.PessimisticReadSelectLockingStrategy;
import org.hibernate.dialect.lock.PessimisticWriteSelectLockingStrategy;
import org.hibernate.dialect.lock.SelectLockingStrategy;
import org.hibernate.engine.jdbc.LobCreator;
import org.hibernate.exception.spi.SQLExceptionConverter;
import org.hibernate.exception.internal.SQLStateConverter;
import org.hibernate.exception.spi.ViolatedConstraintNameExtracter;
import org.hibernate.id.IdentityGenerator;
import org.hibernate.id.SequenceGenerator;
import org.hibernate.id.TableHiLoGenerator;
import org.hibernate.internal.util.ReflectHelper;
import org.hibernate.internal.util.StringHelper;
import org.hibernate.internal.util.collections.ArrayHelper;
import org.hibernate.internal.util.io.StreamCopier;
import org.hibernate.mapping.Column;
import org.hibernate.persister.entity.Lockable;
import org.hibernate.sql.ANSICaseFragment;
import org.hibernate.sql.ANSIJoinFragment;
import org.hibernate.sql.CaseFragment;
import org.hibernate.sql.ForUpdateFragment;
import org.hibernate.sql.JoinFragment;
import org.hibernate.type.StandardBasicTypes;
import org.hibernate.type.descriptor.sql.BlobTypeDescriptor;
import org.hibernate.type.descriptor.sql.ClobTypeDescriptor;
import org.hibernate.type.descriptor.sql.SqlTypeDescriptor;
import org.jboss.logging.Logger;
/**
* Represents a dialect of SQL implemented by a particular RDBMS.
* Subclasses implement Hibernate compatibility with different systems.<br>
* <br>
* Subclasses should provide a public default constructor that <tt>register()
* a set of type mappings and default Hibernate properties.<br>
* <br>
* Subclasses should be immutable.
*
* @author Gavin King, David Channon
*/
public abstract class Dialect {
private static final CoreMessageLogger LOG = Logger.getMessageLogger(CoreMessageLogger.class, Dialect.class.getName());
public static final String DEFAULT_BATCH_SIZE = "15";
public static final String NO_BATCH = "0";
/**
* Characters used for quoting SQL identifiers
*/
public static final String QUOTE = "`\"[";
public static final String CLOSED_QUOTE = "`\"]";
private final TypeNames typeNames = new TypeNames();
private final TypeNames hibernateTypeNames = new TypeNames();
private final Properties properties = new Properties();
private final Map<String, SQLFunction> sqlFunctions = new HashMap();
private final Set<String> sqlKeywords = new HashSet();
// constructors and factory methods ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
protected Dialect() {
LOG.usingDialect(this);
StandardAnsiSqlAggregationFunctions.primeFunctionMap( sqlFunctions );
// standard sql92 functions (can be overridden by subclasses)
registerFunction( "substring", new SQLFunctionTemplate( StandardBasicTypes.STRING, "substring(?1, ?2, ?3)" ) );
registerFunction( "locate", new SQLFunctionTemplate( StandardBasicTypes.INTEGER, "locate(?1, ?2, ?3)" ) );
registerFunction( "trim", new SQLFunctionTemplate( StandardBasicTypes.STRING, "trim(?1 ?2 ?3 ?4)" ) );
registerFunction( "length", new StandardSQLFunction( "length", StandardBasicTypes.INTEGER ) );
registerFunction( "bit_length", new StandardSQLFunction( "bit_length", StandardBasicTypes.INTEGER ) );
registerFunction( "coalesce", new StandardSQLFunction( "coalesce" ) );
registerFunction( "nullif", new StandardSQLFunction( "nullif" ) );
registerFunction( "abs", new StandardSQLFunction( "abs" ) );
registerFunction( "mod", new StandardSQLFunction( "mod", StandardBasicTypes.INTEGER) );
registerFunction( "sqrt", new StandardSQLFunction( "sqrt", StandardBasicTypes.DOUBLE) );
registerFunction( "upper", new StandardSQLFunction("upper") );
registerFunction( "lower", new StandardSQLFunction("lower") );
registerFunction( "cast", new CastFunction() );
registerFunction( "extract", new SQLFunctionTemplate(StandardBasicTypes.INTEGER, "extract(?1 ?2 ?3)") );
//map second/minute/hour/day/month/year to ANSI extract(), override on subclasses
registerFunction( "second", new SQLFunctionTemplate(StandardBasicTypes.INTEGER, "extract(second from ?1)") );
registerFunction( "minute", new SQLFunctionTemplate(StandardBasicTypes.INTEGER, "extract(minute from ?1)") );
registerFunction( "hour", new SQLFunctionTemplate(StandardBasicTypes.INTEGER, "extract(hour from ?1)") );
registerFunction( "day", new SQLFunctionTemplate(StandardBasicTypes.INTEGER, "extract(day from ?1)") );
registerFunction( "month", new SQLFunctionTemplate(StandardBasicTypes.INTEGER, "extract(month from ?1)") );
registerFunction( "year", new SQLFunctionTemplate(StandardBasicTypes.INTEGER, "extract(year from ?1)") );
registerFunction( "str", new SQLFunctionTemplate(StandardBasicTypes.STRING, "cast(?1 as char)") );
registerColumnType( Types.BIT, "bit" );
registerColumnType( Types.BOOLEAN, "boolean" );
registerColumnType( Types.TINYINT, "tinyint" );
registerColumnType( Types.SMALLINT, "smallint" );
registerColumnType( Types.INTEGER, "integer" );
registerColumnType( Types.BIGINT, "bigint" );
registerColumnType( Types.FLOAT, "float($p)" );
registerColumnType( Types.DOUBLE, "double precision" );
registerColumnType( Types.NUMERIC, "numeric($p,$s)" );
registerColumnType( Types.REAL, "real" );
registerColumnType( Types.DATE, "date" );
registerColumnType( Types.TIME, "time" );
registerColumnType( Types.TIMESTAMP, "timestamp" );
registerColumnType( Types.VARBINARY, "bit varying($l)" );
registerColumnType( Types.LONGVARBINARY, "bit varying($l)" );
registerColumnType( Types.BLOB, "blob" );
registerColumnType( Types.CHAR, "char($l)" );
registerColumnType( Types.VARCHAR, "varchar($l)" );
registerColumnType( Types.LONGVARCHAR, "varchar($l)" );
registerColumnType( Types.CLOB, "clob" );
registerColumnType( Types.NCHAR, "nchar($l)" );
registerColumnType( Types.NVARCHAR, "nvarchar($l)" );
registerColumnType( Types.LONGNVARCHAR, "nvarchar($l)" );
registerColumnType( Types.NCLOB, "nclob" );
// register hibernate types for default use in scalar sqlquery type auto detection
registerHibernateType( Types.BIGINT, StandardBasicTypes.BIG_INTEGER.getName() );
registerHibernateType( Types.BINARY, StandardBasicTypes.BINARY.getName() );
registerHibernateType( Types.BIT, StandardBasicTypes.BOOLEAN.getName() );
registerHibernateType( Types.BOOLEAN, StandardBasicTypes.BOOLEAN.getName() );
registerHibernateType( Types.CHAR, StandardBasicTypes.CHARACTER.getName() );
registerHibernateType( Types.DATE, StandardBasicTypes.DATE.getName() );
registerHibernateType( Types.DOUBLE, StandardBasicTypes.DOUBLE.getName() );
registerHibernateType( Types.FLOAT, StandardBasicTypes.FLOAT.getName() );
registerHibernateType( Types.INTEGER, StandardBasicTypes.INTEGER.getName() );
registerHibernateType( Types.SMALLINT, StandardBasicTypes.SHORT.getName() );
registerHibernateType( Types.TINYINT, StandardBasicTypes.BYTE.getName() );
registerHibernateType( Types.TIME, StandardBasicTypes.TIME.getName() );
registerHibernateType( Types.TIMESTAMP, StandardBasicTypes.TIMESTAMP.getName() );
registerHibernateType( Types.VARCHAR, StandardBasicTypes.STRING.getName() );
registerHibernateType( Types.VARBINARY, StandardBasicTypes.BINARY.getName() );
registerHibernateType( Types.LONGVARCHAR, StandardBasicTypes.TEXT.getName() );
registerHibernateType( Types.LONGVARBINARY, StandardBasicTypes.IMAGE.getName() );
registerHibernateType( Types.NUMERIC, StandardBasicTypes.BIG_DECIMAL.getName() );
registerHibernateType( Types.DECIMAL, StandardBasicTypes.BIG_DECIMAL.getName() );
registerHibernateType( Types.BLOB, StandardBasicTypes.BLOB.getName() );
registerHibernateType( Types.CLOB, StandardBasicTypes.CLOB.getName() );
registerHibernateType( Types.REAL, StandardBasicTypes.FLOAT.getName() );
}
/**
* Get an instance of the dialect specified by the current <tt>System properties.
*
* @return The specified Dialect
* @throws HibernateException If no dialect was specified, or if it could not be instantiated.
*/
public static Dialect getDialect() throws HibernateException {
String dialectName = Environment.getProperties().getProperty( Environment.DIALECT );
return instantiateDialect( dialectName );
}
/**
* Get an instance of the dialect specified by the given properties or by
* the current <tt>System properties.
*
* @param props The properties to use for finding the dialect class to use.
* @return The specified Dialect
* @throws HibernateException If no dialect was specified, or if it could not be instantiated.
*/
public static Dialect getDialect(Properties props) throws HibernateException {
String dialectName = props.getProperty( Environment.DIALECT );
if ( dialectName == null ) {
return getDialect();
}
return instantiateDialect( dialectName );
}
private static Dialect instantiateDialect(String dialectName) throws HibernateException {
if ( dialectName == null ) {
throw new HibernateException( "The dialect was not set. Set the property hibernate.dialect." );
}
try {
return ( Dialect ) ReflectHelper.classForName( dialectName ).newInstance();
}
catch ( ClassNotFoundException cnfe ) {
throw new HibernateException( "Dialect class not found: " + dialectName );
}
catch ( Exception e ) {
throw new HibernateException( "Could not instantiate given dialect class: " + dialectName, e );
}
}
/**
* Retrieve a set of default Hibernate properties for this database.
*
* @return a set of Hibernate properties
*/
public final Properties getDefaultProperties() {
return properties;
}
@Override
public String toString() {
return getClass().getName();
}
// database type mapping support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Get the name of the database type associated with the given
* {@link java.sql.Types} typecode.
*
* @param code The {@link java.sql.Types} typecode
* @return the database type name
* @throws HibernateException If no mapping was specified for that type.
*/
public String getTypeName(int code) throws HibernateException {
String result = typeNames.get( code );
if ( result == null ) {
throw new HibernateException( "No default type mapping for (java.sql.Types) " + code );
}
return result;
}
/**
* Get the name of the database type associated with the given
* {@link java.sql.Types} typecode with the given storage specification
* parameters.
*
* @param code The {@link java.sql.Types} typecode
* @param length The datatype length
* @param precision The datatype precision
* @param scale The datatype scale
* @return the database type name
* @throws HibernateException If no mapping was specified for that type.
*/
public String getTypeName(int code, long length, int precision, int scale) throws HibernateException {
String result = typeNames.get( code, length, precision, scale );
if ( result == null ) {
throw new HibernateException(
"No type mapping for java.sql.Types code: " +
code +
", length: " +
length
);
}
return result;
}
/**
* Get the name of the database type appropriate for casting operations
* (via the CAST() SQL function) for the given {@link java.sql.Types} typecode.
*
* @param code The {@link java.sql.Types} typecode
* @return The database type name
*/
public String getCastTypeName(int code) {
return getTypeName( code, Column.DEFAULT_LENGTH, Column.DEFAULT_PRECISION, Column.DEFAULT_SCALE );
}
/**
* Subclasses register a type name for the given type code and maximum
* column length. <tt>$l in the type name with be replaced by the
* column length (if appropriate).
*
* @param code The {@link java.sql.Types} typecode
* @param capacity The maximum length of database type
* @param name The database type name
*/
protected void registerColumnType(int code, long capacity, String name) {
typeNames.put( code, capacity, name );
}
/**
* Subclasses register a type name for the given type code. <tt>$l in
* the type name with be replaced by the column length (if appropriate).
*
* @param code The {@link java.sql.Types} typecode
* @param name The database type name
*/
protected void registerColumnType(int code, String name) {
typeNames.put( code, name );
}
/**
* Allows the dialect to override a {@link SqlTypeDescriptor}.
* <p/>
* If <code>sqlTypeDescriptor is a "standard basic" SQL type
* descriptor, then this method uses {@link #getSqlTypeDescriptorOverride}
* to get an optional override based on the SQL code returned by
* {@link SqlTypeDescriptor#getSqlType()}.
* <p/>
* If this dialect does not provide an override, then this method
* simply returns <code>sqlTypeDescriptor
*
* @param sqlTypeDescriptor The {@link SqlTypeDescriptor} to override
* @return The {@link SqlTypeDescriptor} that should be used for this dialect;
* if there is no override, then <code>sqlTypeDescriptor is returned.
* @throws IllegalArgumentException if <code>sqlTypeDescriptor is null.
*
* @see {@link #getSqlTypeDescriptorOverride}
*/
public SqlTypeDescriptor remapSqlTypeDescriptor(SqlTypeDescriptor sqlTypeDescriptor) {
if ( sqlTypeDescriptor == null ) {
throw new IllegalArgumentException( "sqlTypeDescriptor is null" );
}
if ( ! sqlTypeDescriptor.canBeRemapped() ) {
return sqlTypeDescriptor;
}
final SqlTypeDescriptor overridden = getSqlTypeDescriptorOverride( sqlTypeDescriptor.getSqlType() );
return overridden == null ? sqlTypeDescriptor : overridden;
}
/**
* Returns the {@link SqlTypeDescriptor} that should override the
* "standard basic" SQL type descriptor for values of the specified
* column type, or null, if there is no override.
*
* @param sqlCode A {@link Types} constant indicating the SQL column type
* @return The {@link SqlTypeDescriptor} that should override the
* "standard basic" SQL type descriptor, or null, if there is no override.
*/
protected SqlTypeDescriptor getSqlTypeDescriptorOverride(int sqlCode) {
SqlTypeDescriptor descriptor;
switch ( sqlCode ) {
case Types.BLOB: {
descriptor = useInputStreamToInsertBlob() ? BlobTypeDescriptor.STREAM_BINDING : null;
break;
}
case Types.CLOB: {
descriptor = useInputStreamToInsertBlob() ? ClobTypeDescriptor.STREAM_BINDING : null;
break;
}
default: {
descriptor = null;
break;
}
}
return descriptor;
}
/**
* The legacy behavior of Hibernate. LOBs are not processed by merge
*/
protected static final LobMergeStrategy LEGACY_LOB_MERGE_STRATEGY = new LobMergeStrategy() {
@Override
public Blob mergeBlob(Blob original, Blob target, SessionImplementor session) {
return target;
}
@Override
public Clob mergeClob(Clob original, Clob target, SessionImplementor session) {
return target;
}
@Override
public NClob mergeNClob(NClob original, NClob target, SessionImplementor session) {
return target;
}
};
/**
* Merge strategy based on transferring contents based on streams.
*/
protected static final LobMergeStrategy STREAM_XFER_LOB_MERGE_STRATEGY = new LobMergeStrategy() {
@Override
public Blob mergeBlob(Blob original, Blob target, SessionImplementor session) {
if ( original != target ) {
try {
OutputStream connectedStream = target.setBinaryStream( 1L ); // the BLOB just read during the load phase of merge
InputStream detachedStream = original.getBinaryStream(); // the BLOB from the detached state
StreamCopier.copy( detachedStream, connectedStream );
return target;
}
catch (SQLException e ) {
throw session.getFactory().getSQLExceptionHelper().convert( e, "unable to merge BLOB data" );
}
}
else {
return NEW_LOCATOR_LOB_MERGE_STRATEGY.mergeBlob( original, target, session );
}
}
@Override
public Clob mergeClob(Clob original, Clob target, SessionImplementor session) {
if ( original != target ) {
try {
OutputStream connectedStream = target.setAsciiStream( 1L ); // the CLOB just read during the load phase of merge
InputStream detachedStream = original.getAsciiStream(); // the CLOB from the detached state
StreamCopier.copy( detachedStream, connectedStream );
return target;
}
catch (SQLException e ) {
throw session.getFactory().getSQLExceptionHelper().convert( e, "unable to merge CLOB data" );
}
}
else {
return NEW_LOCATOR_LOB_MERGE_STRATEGY.mergeClob( original, target, session );
}
}
@Override
public NClob mergeNClob(NClob original, NClob target, SessionImplementor session) {
if ( original != target ) {
try {
OutputStream connectedStream = target.setAsciiStream( 1L ); // the NCLOB just read during the load phase of merge
InputStream detachedStream = original.getAsciiStream(); // the NCLOB from the detached state
StreamCopier.copy( detachedStream, connectedStream );
return target;
}
catch (SQLException e ) {
throw session.getFactory().getSQLExceptionHelper().convert( e, "unable to merge NCLOB data" );
}
}
else {
return NEW_LOCATOR_LOB_MERGE_STRATEGY.mergeNClob( original, target, session );
}
}
};
/**
* Merge strategy based on creating a new LOB locator.
*/
protected static final LobMergeStrategy NEW_LOCATOR_LOB_MERGE_STRATEGY = new LobMergeStrategy() {
@Override
public Blob mergeBlob(Blob original, Blob target, SessionImplementor session) {
if ( original == null && target == null ) {
return null;
}
try {
LobCreator lobCreator = session.getFactory().getJdbcServices().getLobCreator( session );
return original == null
? lobCreator.createBlob( ArrayHelper.EMPTY_BYTE_ARRAY )
: lobCreator.createBlob( original.getBinaryStream(), original.length() );
}
catch (SQLException e) {
throw session.getFactory().getSQLExceptionHelper().convert( e, "unable to merge BLOB data" );
}
}
@Override
public Clob mergeClob(Clob original, Clob target, SessionImplementor session) {
if ( original == null && target == null ) {
return null;
}
try {
LobCreator lobCreator = session.getFactory().getJdbcServices().getLobCreator( session );
return original == null
? lobCreator.createClob( "" )
: lobCreator.createClob( original.getCharacterStream(), original.length() );
}
catch (SQLException e) {
throw session.getFactory().getSQLExceptionHelper().convert( e, "unable to merge CLOB data" );
}
}
@Override
public NClob mergeNClob(NClob original, NClob target, SessionImplementor session) {
if ( original == null && target == null ) {
return null;
}
try {
LobCreator lobCreator = session.getFactory().getJdbcServices().getLobCreator( session );
return original == null
? lobCreator.createNClob( "" )
: lobCreator.createNClob( original.getCharacterStream(), original.length() );
}
catch (SQLException e) {
throw session.getFactory().getSQLExceptionHelper().convert( e, "unable to merge NCLOB data" );
}
}
};
public LobMergeStrategy getLobMergeStrategy() {
return NEW_LOCATOR_LOB_MERGE_STRATEGY;
}
// hibernate type mapping support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Get the name of the Hibernate {@link org.hibernate.type.Type} associated with the given
* {@link java.sql.Types} typecode.
*
* @param code The {@link java.sql.Types} typecode
* @return The Hibernate {@link org.hibernate.type.Type} name.
* @throws HibernateException If no mapping was specified for that type.
*/
public String getHibernateTypeName(int code) throws HibernateException {
String result = hibernateTypeNames.get( code );
if ( result == null ) {
throw new HibernateException( "No Hibernate type mapping for java.sql.Types code: " + code );
}
return result;
}
/**
* Get the name of the Hibernate {@link org.hibernate.type.Type} associated
* with the given {@link java.sql.Types} typecode with the given storage
* specification parameters.
*
* @param code The {@link java.sql.Types} typecode
* @param length The datatype length
* @param precision The datatype precision
* @param scale The datatype scale
* @return The Hibernate {@link org.hibernate.type.Type} name.
* @throws HibernateException If no mapping was specified for that type.
*/
public String getHibernateTypeName(int code, int length, int precision, int scale) throws HibernateException {
String result = hibernateTypeNames.get( code, length, precision, scale );
if ( result == null ) {
throw new HibernateException(
"No Hibernate type mapping for java.sql.Types code: " +
code +
", length: " +
length
);
}
return result;
}
/**
* Registers a Hibernate {@link org.hibernate.type.Type} name for the given
* {@link java.sql.Types} type code and maximum column length.
*
* @param code The {@link java.sql.Types} typecode
* @param capacity The maximum length of database type
* @param name The Hibernate {@link org.hibernate.type.Type} name
*/
protected void registerHibernateType(int code, long capacity, String name) {
hibernateTypeNames.put( code, capacity, name);
}
/**
* Registers a Hibernate {@link org.hibernate.type.Type} name for the given
* {@link java.sql.Types} type code.
*
* @param code The {@link java.sql.Types} typecode
* @param name The Hibernate {@link org.hibernate.type.Type} name
*/
protected void registerHibernateType(int code, String name) {
hibernateTypeNames.put( code, name);
}
// function support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
protected void registerFunction(String name, SQLFunction function) {
sqlFunctions.put( name, function );
}
/**
* Retrieves a map of the dialect's registered functions
* (functionName => {@link org.hibernate.dialect.function.SQLFunction}).
*
* @return The map of registered functions.
*/
public final Map<String, SQLFunction> getFunctions() {
return sqlFunctions;
}
// keyword support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
protected void registerKeyword(String word) {
sqlKeywords.add(word);
}
public Set<String> getKeywords() {
return sqlKeywords;
}
// native identifier generation ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* The class (which implements {@link org.hibernate.id.IdentifierGenerator})
* which acts as this dialects native generation strategy.
* <p/>
* Comes into play whenever the user specifies the native generator.
*
* @return The native generator class.
*/
public Class getNativeIdentifierGeneratorClass() {
if ( supportsIdentityColumns() ) {
return IdentityGenerator.class;
}
else if ( supportsSequences() ) {
return SequenceGenerator.class;
}
else {
return TableHiLoGenerator.class;
}
}
// IDENTITY support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Does this dialect support identity column key generation?
*
* @return True if IDENTITY columns are supported; false otherwise.
*/
public boolean supportsIdentityColumns() {
return false;
}
/**
* Does the dialect support some form of inserting and selecting
* the generated IDENTITY value all in the same statement.
*
* @return True if the dialect supports selecting the just
* generated IDENTITY in the insert statement.
*/
public boolean supportsInsertSelectIdentity() {
return false;
}
/**
* Whether this dialect have an Identity clause added to the data type or a
* completely separate identity data type
*
* @return boolean
*/
public boolean hasDataTypeInIdentityColumn() {
return true;
}
/**
* Provided we {@link #supportsInsertSelectIdentity}, then attach the
* "select identity" clause to the insert statement.
* <p/>
* Note, if {@link #supportsInsertSelectIdentity} == false then
* the insert-string should be returned without modification.
*
* @param insertString The insert command
* @return The insert command with any necessary identity select
* clause attached.
*/
public String appendIdentitySelectToInsert(String insertString) {
return insertString;
}
/**
* Get the select command to use to retrieve the last generated IDENTITY
* value for a particular table
*
* @param table The table into which the insert was done
* @param column The PK column.
* @param type The {@link java.sql.Types} type code.
* @return The appropriate select command
* @throws MappingException If IDENTITY generation is not supported.
*/
public String getIdentitySelectString(String table, String column, int type) throws MappingException {
return getIdentitySelectString();
}
/**
* Get the select command to use to retrieve the last generated IDENTITY
* value.
*
* @return The appropriate select command
* @throws MappingException If IDENTITY generation is not supported.
*/
protected String getIdentitySelectString() throws MappingException {
throw new MappingException( getClass().getName() + " does not support identity key generation" );
}
/**
* The syntax used during DDL to define a column as being an IDENTITY of
* a particular type.
*
* @param type The {@link java.sql.Types} type code.
* @return The appropriate DDL fragment.
* @throws MappingException If IDENTITY generation is not supported.
*/
public String getIdentityColumnString(int type) throws MappingException {
return getIdentityColumnString();
}
/**
* The syntax used during DDL to define a column as being an IDENTITY.
*
* @return The appropriate DDL fragment.
* @throws MappingException If IDENTITY generation is not supported.
*/
protected String getIdentityColumnString() throws MappingException {
throw new MappingException( getClass().getName() + " does not support identity key generation" );
}
/**
* The keyword used to insert a generated value into an identity column (or null).
* Need if the dialect does not support inserts that specify no column values.
*
* @return The appropriate keyword.
*/
public String getIdentityInsertString() {
return null;
}
// SEQUENCE support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Does this dialect support sequences?
*
* @return True if sequences supported; false otherwise.
*/
public boolean supportsSequences() {
return false;
}
/**
* Does this dialect support "pooled" sequences. Not aware of a better
* name for this. Essentially can we specify the initial and increment values?
*
* @return True if such "pooled" sequences are supported; false otherwise.
* @see #getCreateSequenceStrings(String, int, int)
* @see #getCreateSequenceString(String, int, int)
*/
public boolean supportsPooledSequences() {
return false;
}
/**
* Generate the appropriate select statement to to retrieve the next value
* of a sequence.
* <p/>
* This should be a "stand alone" select statement.
*
* @param sequenceName the name of the sequence
* @return String The "nextval" select string.
* @throws MappingException If sequences are not supported.
*/
public String getSequenceNextValString(String sequenceName) throws MappingException {
throw new MappingException( getClass().getName() + " does not support sequences" );
}
/**
* Generate the select expression fragment that will retrieve the next
* value of a sequence as part of another (typically DML) statement.
* <p/>
* This differs from {@link #getSequenceNextValString(String)} in that this
* should return an expression usable within another statement.
*
* @param sequenceName the name of the sequence
* @return The "nextval" fragment.
* @throws MappingException If sequences are not supported.
*/
public String getSelectSequenceNextValString(String sequenceName) throws MappingException {
throw new MappingException( getClass().getName() + " does not support sequences" );
}
/**
* The multiline script used to create a sequence.
*
* @param sequenceName The name of the sequence
* @return The sequence creation commands
* @throws MappingException If sequences are not supported.
* @deprecated Use {@link #getCreateSequenceString(String, int, int)} instead
*/
@Deprecated
public String[] getCreateSequenceStrings(String sequenceName) throws MappingException {
return new String[] { getCreateSequenceString( sequenceName ) };
}
/**
* An optional multi-line form for databases which {@link #supportsPooledSequences()}.
*
* @param sequenceName The name of the sequence
* @param initialValue The initial value to apply to 'create sequence' statement
* @param incrementSize The increment value to apply to 'create sequence' statement
* @return The sequence creation commands
* @throws MappingException If sequences are not supported.
*/
public String[] getCreateSequenceStrings(String sequenceName, int initialValue, int incrementSize) throws MappingException {
return new String[] { getCreateSequenceString( sequenceName, initialValue, incrementSize ) };
}
/**
* Typically dialects which support sequences can create a sequence
* with a single command. This is convenience form of
* {@link #getCreateSequenceStrings} to help facilitate that.
* <p/>
* Dialects which support sequences and can create a sequence in a
* single command need *only* override this method. Dialects
* which support sequences but require multiple commands to create
* a sequence should instead override {@link #getCreateSequenceStrings}.
*
* @param sequenceName The name of the sequence
* @return The sequence creation command
* @throws MappingException If sequences are not supported.
*/
protected String getCreateSequenceString(String sequenceName) throws MappingException {
throw new MappingException( getClass().getName() + " does not support sequences" );
}
/**
* Overloaded form of {@link #getCreateSequenceString(String)}, additionally
* taking the initial value and increment size to be applied to the sequence
* definition.
* </p>
* The default definition is to suffix {@link #getCreateSequenceString(String)}
* with the string: " start with {initialValue} increment by {incrementSize}" where
* {initialValue} and {incrementSize} are replacement placeholders. Generally
* dialects should only need to override this method if different key phrases
* are used to apply the allocation information.
*
* @param sequenceName The name of the sequence
* @param initialValue The initial value to apply to 'create sequence' statement
* @param incrementSize The increment value to apply to 'create sequence' statement
* @return The sequence creation command
* @throws MappingException If sequences are not supported.
*/
protected String getCreateSequenceString(String sequenceName, int initialValue, int incrementSize) throws MappingException {
if ( supportsPooledSequences() ) {
return getCreateSequenceString( sequenceName ) + " start with " + initialValue + " increment by " + incrementSize;
}
throw new MappingException( getClass().getName() + " does not support pooled sequences" );
}
/**
* The multiline script used to drop a sequence.
*
* @param sequenceName The name of the sequence
* @return The sequence drop commands
* @throws MappingException If sequences are not supported.
*/
public String[] getDropSequenceStrings(String sequenceName) throws MappingException {
return new String[]{getDropSequenceString( sequenceName )};
}
/**
* Typically dialects which support sequences can drop a sequence
* with a single command. This is convenience form of
* {@link #getDropSequenceStrings} to help facilitate that.
* <p/>
* Dialects which support sequences and can drop a sequence in a
* single command need *only* override this method. Dialects
* which support sequences but require multiple commands to drop
* a sequence should instead override {@link #getDropSequenceStrings}.
*
* @param sequenceName The name of the sequence
* @return The sequence drop commands
* @throws MappingException If sequences are not supported.
*/
protected String getDropSequenceString(String sequenceName) throws MappingException {
throw new MappingException( getClass().getName() + " does not support sequences" );
}
/**
* Get the select command used retrieve the names of all sequences.
*
* @return The select command; or null if sequences are not supported.
* @see org.hibernate.tool.hbm2ddl.SchemaUpdate
*/
public String getQuerySequencesString() {
return null;
}
// GUID support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Get the command used to select a GUID from the underlying database.
* <p/>
* Optional operation.
*
* @return The appropriate command.
*/
public String getSelectGUIDString() {
throw new UnsupportedOperationException( getClass().getName() + " does not support GUIDs" );
}
// limit/offset support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Does this dialect support some form of limiting query results
* via a SQL clause?
*
* @return True if this dialect supports some form of LIMIT.
*/
public boolean supportsLimit() {
return false;
}
/**
* Does this dialect's LIMIT support (if any) additionally
* support specifying an offset?
*
* @return True if the dialect supports an offset within the limit support.
*/
public boolean supportsLimitOffset() {
return supportsLimit();
}
/**
* Does this dialect support bind variables (i.e., prepared statement
* parameters) for its limit/offset?
*
* @return True if bind variables can be used; false otherwise.
*/
public boolean supportsVariableLimit() {
return supportsLimit();
}
/**
* ANSI SQL defines the LIMIT clause to be in the form LIMIT offset, limit.
* Does this dialect require us to bind the parameters in reverse order?
*
* @return true if the correct order is limit, offset
*/
public boolean bindLimitParametersInReverseOrder() {
return false;
}
/**
* Does the <tt>LIMIT clause come at the start of the
* <tt>SELECT statement, rather than at the end?
*
* @return true if limit parameters should come before other parameters
*/
public boolean bindLimitParametersFirst() {
return false;
}
/**
* Does the <tt>LIMIT clause take a "maximum" row number instead
* of a total number of returned rows?
* <p/>
* This is easiest understood via an example. Consider you have a table
* with 20 rows, but you only want to retrieve rows number 11 through 20.
* Generally, a limit with offset would say that the offset = 11 and the
* limit = 10 (we only want 10 rows at a time); this is specifying the
* total number of returned rows. Some dialects require that we instead
* specify offset = 11 and limit = 20, where 20 is the "last" row we want
* relative to offset (i.e. total number of rows = 20 - 11 = 9)
* <p/>
* So essentially, is limit relative from offset? Or is limit absolute?
*
* @return True if limit is relative from offset; false otherwise.
*/
public boolean useMaxForLimit() {
return false;
}
/**
* Generally, if there is no limit applied to a Hibernate query we do not apply any limits
* to the SQL query. This option forces that the limit be written to the SQL query.
*
* @return True to force limit into SQL query even if none specified in Hibernate query; false otherwise.
*/
public boolean forceLimitUsage() {
return false;
}
/**
* Given a limit and an offset, apply the limit clause to the query.
*
* @param query The query to which to apply the limit.
* @param offset The offset of the limit
* @param limit The limit of the limit ;)
* @return The modified query statement with the limit applied.
*/
public String getLimitString(String query, int offset, int limit) {
return getLimitString( query, ( offset > 0 || forceLimitUsage() ) );
}
/**
* Apply s limit clause to the query.
* <p/>
* Typically dialects utilize {@link #supportsVariableLimit() variable}
* limit clauses when they support limits. Thus, when building the
* select command we do not actually need to know the limit or the offest
* since we will just be using placeholders.
* <p/>
* Here we do still pass along whether or not an offset was specified
* so that dialects not supporting offsets can generate proper exceptions.
* In general, dialects will override one or the other of this method and
* {@link #getLimitString(String, int, int)}.
*
* @param query The query to which to apply the limit.
* @param hasOffset Is the query requesting an offset?
* @return the modified SQL
*/
protected String getLimitString(String query, boolean hasOffset) {
throw new UnsupportedOperationException( "Paged queries not supported by " + getClass().getName());
}
/**
* Hibernate APIs explicitly state that setFirstResult() should be a zero-based offset. Here we allow the
* Dialect a chance to convert that value based on what the underlying db or driver will expect.
* <p/>
* NOTE: what gets passed into {@link #getLimitString(String,int,int)} is the zero-based offset. Dialects which
* do not {@link #supportsVariableLimit} should take care to perform any needed {@link #convertToFirstRowValue}
* calls prior to injecting the limit values into the SQL string.
*
* @param zeroBasedFirstResult The user-supplied, zero-based first row offset.
*
* @return The corresponding db/dialect specific offset.
*
* @see org.hibernate.Query#setFirstResult
* @see org.hibernate.Criteria#setFirstResult
*/
public int convertToFirstRowValue(int zeroBasedFirstResult) {
return zeroBasedFirstResult;
}
// lock acquisition support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Informational metadata about whether this dialect is known to support
* specifying timeouts for requested lock acquisitions.
*
* @return True is this dialect supports specifying lock timeouts.
*/
public boolean supportsLockTimeouts() {
return true;
}
/**
* If this dialect supports specifying lock timeouts, are those timeouts
* rendered into the <tt>SQL string as parameters. The implication
* is that Hibernate will need to bind the timeout value as a parameter
* in the {@link java.sql.PreparedStatement}. If true, the param position
* is always handled as the last parameter; if the dialect specifies the
* lock timeout elsewhere in the <tt>SQL statement then the timeout
* value should be directly rendered into the statement and this method
* should return false.
*
* @return True if the lock timeout is rendered into the <tt>SQL
* string as a parameter; false otherwise.
*/
public boolean isLockTimeoutParameterized() {
return false;
}
/**
* Get a strategy instance which knows how to acquire a database-level lock
* of the specified mode for this dialect.
*
* @param lockable The persister for the entity to be locked.
* @param lockMode The type of lock to be acquired.
* @return The appropriate locking strategy.
* @since 3.2
*/
public LockingStrategy getLockingStrategy(Lockable lockable, LockMode lockMode) {
switch ( lockMode ) {
case PESSIMISTIC_FORCE_INCREMENT:
return new PessimisticForceIncrementLockingStrategy( lockable, lockMode );
case PESSIMISTIC_WRITE:
return new PessimisticWriteSelectLockingStrategy( lockable, lockMode );
case PESSIMISTIC_READ:
return new PessimisticReadSelectLockingStrategy( lockable, lockMode );
case OPTIMISTIC:
return new OptimisticLockingStrategy( lockable, lockMode );
case OPTIMISTIC_FORCE_INCREMENT:
return new OptimisticForceIncrementLockingStrategy( lockable, lockMode );
default:
return new SelectLockingStrategy( lockable, lockMode );
}
}
/**
* Given LockOptions (lockMode, timeout), determine the appropriate for update fragment to use.
*
* @param lockOptions contains the lock mode to apply.
* @return The appropriate for update fragment.
*/
public String getForUpdateString(LockOptions lockOptions) {
LockMode lockMode = lockOptions.getLockMode();
return getForUpdateString( lockMode, lockOptions.getTimeOut() );
}
private String getForUpdateString(LockMode lockMode, int timeout){
switch ( lockMode ) {
case UPGRADE:
return getForUpdateString();
case PESSIMISTIC_READ:
return getReadLockString( timeout );
case PESSIMISTIC_WRITE:
return getWriteLockString( timeout );
case UPGRADE_NOWAIT:
case FORCE:
case PESSIMISTIC_FORCE_INCREMENT:
return getForUpdateNowaitString();
default:
return "";
}
}
/**
* Given a lock mode, determine the appropriate for update fragment to use.
*
* @param lockMode The lock mode to apply.
* @return The appropriate for update fragment.
*/
public String getForUpdateString(LockMode lockMode) {
return getForUpdateString( lockMode, LockOptions.WAIT_FOREVER );
}
/**
* Get the string to append to SELECT statements to acquire locks
* for this dialect.
*
* @return The appropriate <tt>FOR UPDATE clause string.
*/
public String getForUpdateString() {
return " for update";
}
/**
* Get the string to append to SELECT statements to acquire WRITE locks
* for this dialect. Location of the of the returned string is treated
* the same as getForUpdateString.
*
* @param timeout in milliseconds, -1 for indefinite wait and 0 for no wait.
* @return The appropriate <tt>LOCK clause string.
*/
public String getWriteLockString(int timeout) {
return getForUpdateString();
}
/**
* Get the string to append to SELECT statements to acquire WRITE locks
* for this dialect. Location of the of the returned string is treated
* the same as getForUpdateString.
*
* @param timeout in milliseconds, -1 for indefinite wait and 0 for no wait.
* @return The appropriate <tt>LOCK clause string.
*/
public String getReadLockString(int timeout) {
return getForUpdateString();
}
/**
* Is <tt>FOR UPDATE OF syntax supported?
*
* @return True if the database supports <tt>FOR UPDATE OF syntax;
* false otherwise.
*/
public boolean forUpdateOfColumns() {
// by default we report no support
return false;
}
/**
* Does this dialect support <tt>FOR UPDATE in conjunction with
* outer joined rows?
*
* @return True if outer joined rows can be locked via <tt>FOR UPDATE.
*/
public boolean supportsOuterJoinForUpdate() {
return true;
}
/**
* Get the <tt>FOR UPDATE OF column_list fragment appropriate for this
* dialect given the aliases of the columns to be write locked.
*
* @param aliases The columns to be write locked.
* @return The appropriate <tt>FOR UPDATE OF column_list clause string.
*/
public String getForUpdateString(String aliases) {
// by default we simply return the getForUpdateString() result since
// the default is to say no support for "FOR UPDATE OF ..."
return getForUpdateString();
}
/**
* Get the <tt>FOR UPDATE OF column_list fragment appropriate for this
* dialect given the aliases of the columns to be write locked.
*
* @param aliases The columns to be write locked.
* @param lockOptions
* @return The appropriate <tt>FOR UPDATE OF column_list clause string.
*/
public String getForUpdateString(String aliases, LockOptions lockOptions) {
// by default we simply return the getForUpdateString() result since
// the default is to say no support for "FOR UPDATE OF ..."
return getForUpdateString(lockOptions);
}
/**
* Retrieves the <tt>FOR UPDATE NOWAIT syntax specific to this dialect.
*
* @return The appropriate <tt>FOR UPDATE NOWAIT clause string.
*/
public String getForUpdateNowaitString() {
// by default we report no support for NOWAIT lock semantics
return getForUpdateString();
}
/**
* Get the <tt>FOR UPDATE OF column_list NOWAIT fragment appropriate
* for this dialect given the aliases of the columns to be write locked.
*
* @param aliases The columns to be write locked.
* @return The appropriate <tt>FOR UPDATE colunm_list NOWAIT clause string.
*/
public String getForUpdateNowaitString(String aliases) {
return getForUpdateString( aliases );
}
/**
* Some dialects support an alternative means to <tt>SELECT FOR UPDATE,
* whereby a "lock hint" is appends to the table name in the from clause.
* <p/>
* contributed by <a href="http://sourceforge.net/users/heschulz">Helge Schulz
*
* @param mode The lock mode to apply
* @param tableName The name of the table to which to apply the lock hint.
* @return The table with any required lock hints.
*/
public String appendLockHint(LockMode mode, String tableName) {
return tableName;
}
/**
* Modifies the given SQL by applying the appropriate updates for the specified
* lock modes and key columns.
* <p/>
* The behavior here is that of an ANSI SQL <tt>SELECT FOR UPDATE. This
* method is really intended to allow dialects which do not support
* <tt>SELECT FOR UPDATE to achieve this in their own fashion.
*
* @param sql the SQL string to modify
* @param aliasedLockOptions lock options indexed by aliased table names.
* @param keyColumnNames a map of key columns indexed by aliased table names.
* @return the modified SQL string.
*/
public String applyLocksToSql(String sql, LockOptions aliasedLockOptions, Map keyColumnNames) {
return sql + new ForUpdateFragment( this, aliasedLockOptions, keyColumnNames ).toFragmentString();
}
// table support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Command used to create a table.
*
* @return The command used to create a table.
*/
public String getCreateTableString() {
return "create table";
}
/**
* Slight variation on {@link #getCreateTableString}. Here, we have the
* command used to create a table when there is no primary key and
* duplicate rows are expected.
* <p/>
* Most databases do not care about the distinction; originally added for
* Teradata support which does care.
*
* @return The command used to create a multiset table.
*/
public String getCreateMultisetTableString() {
return getCreateTableString();
}
// temporary table support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Does this dialect support temporary tables?
*
* @return True if temp tables are supported; false otherwise.
*/
public boolean supportsTemporaryTables() {
return false;
}
/**
* Generate a temporary table name given the base table.
*
* @param baseTableName The table name from which to base the temp table name.
* @return The generated temp table name.
*/
public String generateTemporaryTableName(String baseTableName) {
return "HT_" + baseTableName;
}
/**
* Command used to create a temporary table.
*
* @return The command used to create a temporary table.
*/
public String getCreateTemporaryTableString() {
return "create table";
}
/**
* Get any fragments needing to be postfixed to the command for
* temporary table creation.
*
* @return Any required postfix.
*/
public String getCreateTemporaryTablePostfix() {
return "";
}
/**
* Command used to drop a temporary table.
*
* @return The command used to drop a temporary table.
*/
public String getDropTemporaryTableString() {
return "drop table";
}
/**
* Does the dialect require that temporary table DDL statements occur in
* isolation from other statements? This would be the case if the creation
* would cause any current transaction to get committed implicitly.
* <p/>
* JDBC defines a standard way to query for this information via the
* {@link java.sql.DatabaseMetaData#dataDefinitionCausesTransactionCommit()}
* method. However, that does not distinguish between temporary table
* DDL and other forms of DDL; MySQL, for example, reports DDL causing a
* transaction commit via its driver, even though that is not the case for
* temporary table DDL.
* <p/>
* Possible return values and their meanings:<ul>
* <li>{@link Boolean#TRUE} - Unequivocally, perform the temporary table DDL
* in isolation.</li>
* <li>{@link Boolean#FALSE} - Unequivocally, do not perform the
* temporary table DDL in isolation.</li>
* <li>null - defer to the JDBC driver response in regards to
* {@link java.sql.DatabaseMetaData#dataDefinitionCausesTransactionCommit()}</li>
* </ul>
*
* @return see the result matrix above.
*/
public Boolean performTemporaryTableDDLInIsolation() {
return null;
}
/**
* Do we need to drop the temporary table after use?
*
* @return True if the table should be dropped.
*/
public boolean dropTemporaryTableAfterUse() {
return true;
}
// callable statement support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Registers an OUT parameter which will be returning a
* {@link java.sql.ResultSet}. How this is accomplished varies greatly
* from DB to DB, hence its inclusion (along with {@link #getResultSet}) here.
*
* @param statement The callable statement.
* @param position The bind position at which to register the OUT param.
* @return The number of (contiguous) bind positions used.
* @throws SQLException Indicates problems registering the OUT param.
*/
public int registerResultSetOutParameter(CallableStatement statement, int position) throws SQLException {
throw new UnsupportedOperationException(
getClass().getName() +
" does not support resultsets via stored procedures"
);
}
/**
* Given a callable statement previously processed by {@link #registerResultSetOutParameter},
* extract the {@link java.sql.ResultSet} from the OUT parameter.
*
* @param statement The callable statement.
* @return The extracted result set.
* @throws SQLException Indicates problems extracting the result set.
*/
public ResultSet getResultSet(CallableStatement statement) throws SQLException {
throw new UnsupportedOperationException(
getClass().getName() +
" does not support resultsets via stored procedures"
);
}
// current timestamp support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Does this dialect support a way to retrieve the database's current
* timestamp value?
*
* @return True if the current timestamp can be retrieved; false otherwise.
*/
public boolean supportsCurrentTimestampSelection() {
return false;
}
/**
* Should the value returned by {@link #getCurrentTimestampSelectString}
* be treated as callable. Typically this indicates that JDBC escape
* syntax is being used...
*
* @return True if the {@link #getCurrentTimestampSelectString} return
* is callable; false otherwise.
*/
public boolean isCurrentTimestampSelectStringCallable() {
throw new UnsupportedOperationException( "Database not known to define a current timestamp function" );
}
/**
* Retrieve the command used to retrieve the current timestamp from the
* database.
*
* @return The command.
*/
public String getCurrentTimestampSelectString() {
throw new UnsupportedOperationException( "Database not known to define a current timestamp function" );
}
/**
* The name of the database-specific SQL function for retrieving the
* current timestamp.
*
* @return The function name.
*/
public String getCurrentTimestampSQLFunctionName() {
// the standard SQL function name is current_timestamp...
return "current_timestamp";
}
// SQLException support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Build an instance of the SQLExceptionConverter preferred by this dialect for
* converting SQLExceptions into Hibernate's JDBCException hierarchy. The default
* Dialect implementation simply returns a converter based on X/Open SQLState codes.
* <p/>
* It is strongly recommended that specific Dialect implementations override this
* method, since interpretation of a SQL error is much more accurate when based on
* the ErrorCode rather than the SQLState. Unfortunately, the ErrorCode is a vendor-
* specific approach.
*
* @return The Dialect's preferred SQLExceptionConverter.
*/
public SQLExceptionConverter buildSQLExceptionConverter() {
// The default SQLExceptionConverter for all dialects is based on SQLState
// since SQLErrorCode is extremely vendor-specific. Specific Dialects
// may override to return whatever is most appropriate for that vendor.
return new SQLStateConverter( getViolatedConstraintNameExtracter() );
}
private static final ViolatedConstraintNameExtracter EXTRACTER = new ViolatedConstraintNameExtracter() {
public String extractConstraintName(SQLException sqle) {
return null;
}
};
public ViolatedConstraintNameExtracter getViolatedConstraintNameExtracter() {
return EXTRACTER;
}
// union subclass support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Given a {@link java.sql.Types} type code, determine an appropriate
* null value to use in a select clause.
* <p/>
* One thing to consider here is that certain databases might
* require proper casting for the nulls here since the select here
* will be part of a UNION/UNION ALL.
*
* @param sqlType The {@link java.sql.Types} type code.
* @return The appropriate select clause value fragment.
*/
public String getSelectClauseNullString(int sqlType) {
return "null";
}
/**
* Does this dialect support UNION ALL, which is generally a faster
* variant of UNION?
*
* @return True if UNION ALL is supported; false otherwise.
*/
public boolean supportsUnionAll() {
return false;
}
// miscellaneous support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Create a {@link org.hibernate.sql.JoinFragment} strategy responsible
* for handling this dialect's variations in how joins are handled.
*
* @return This dialect's {@link org.hibernate.sql.JoinFragment} strategy.
*/
public JoinFragment createOuterJoinFragment() {
return new ANSIJoinFragment();
}
/**
* Create a {@link org.hibernate.sql.CaseFragment} strategy responsible
* for handling this dialect's variations in how CASE statements are
* handled.
*
* @return This dialect's {@link org.hibernate.sql.CaseFragment} strategy.
*/
public CaseFragment createCaseFragment() {
return new ANSICaseFragment();
}
/**
* The fragment used to insert a row without specifying any column values.
* This is not possible on some databases.
*
* @return The appropriate empty values clause.
*/
public String getNoColumnsInsertString() {
return "values ( )";
}
/**
* The name of the SQL function that transforms a string to
* lowercase
*
* @return The dialect-specific lowercase function.
*/
public String getLowercaseFunction() {
return "lower";
}
/**
* The name of the SQL function that can do case insensitive <b>like comparison.
* @return The dialect-specific "case insensitive" like function.
*/
public String getCaseInsensitiveLike(){
return "like";
}
/**
* Does the underlying Database supports case insensitive like comparison.
*/
public boolean supportsCaseInsensitiveLike(){
return false;
}
/**
* Meant as a means for end users to affect the select strings being sent
* to the database and perhaps manipulate them in some fashion.
* <p/>
* The recommend approach is to instead use
* {@link org.hibernate.Interceptor#onPrepareStatement(String)}.
*
* @param select The select command
* @return The mutated select command, or the same as was passed in.
*/
public String transformSelectString(String select) {
return select;
}
/**
* What is the maximum length Hibernate can use for generated aliases?
*
* @return The maximum length.
*/
public int getMaxAliasLength() {
return 10;
}
/**
* The SQL literal value to which this database maps boolean values.
*
* @param bool The boolean value
* @return The appropriate SQL literal.
*/
public String toBooleanValueString(boolean bool) {
return bool ? "1" : "0";
}
// identifier quoting support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* The character specific to this dialect used to begin a quoted identifier.
*
* @return The dialect's specific open quote character.
*/
public char openQuote() {
return '"';
}
/**
* The character specific to this dialect used to close a quoted identifier.
*
* @return The dialect's specific close quote character.
*/
public char closeQuote() {
return '"';
}
/**
* Apply dialect-specific quoting.
* <p/>
* By default, the incoming value is checked to see if its first character
* is the back-tick (`). If so, the dialect specific quoting is applied.
*
* @param name The value to be quoted.
* @return The quoted (or unmodified, if not starting with back-tick) value.
* @see #openQuote()
* @see #closeQuote()
*/
public final String quote(String name) {
if ( name == null ) {
return null;
}
if ( name.charAt( 0 ) == '`' ) {
return openQuote() + name.substring( 1, name.length() - 1 ) + closeQuote();
}
else {
return name;
}
}
// DDL support ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Does this dialect support the <tt>ALTER TABLE syntax?
*
* @return True if we support altering of tables; false otherwise.
*/
public boolean hasAlterTable() {
return true;
}
/**
* Do we need to drop constraints before dropping tables in this dialect?
*
* @return True if constraints must be dropped prior to dropping
* the table; false otherwise.
*/
public boolean dropConstraints() {
return true;
}
/**
* Do we need to qualify index names with the schema name?
*
* @return boolean
*/
public boolean qualifyIndexName() {
return true;
}
/**
* Does this dialect support the <tt>UNIQUE column syntax?
*
* @return boolean
*/
public boolean supportsUnique() {
return true;
}
/**
* Does this dialect support adding Unique constraints via create and alter table ?
* @return boolean
*/
public boolean supportsUniqueConstraintInCreateAlterTable() {
return true;
}
/**
* The syntax used to add a column to a table (optional).
*
* @return The "add column" fragment.
*/
public String getAddColumnString() {
throw new UnsupportedOperationException( "No add column syntax supported by " + getClass().getName() );
}
public String getDropForeignKeyString() {
return " drop constraint ";
}
public String getTableTypeString() {
// grrr... for differentiation of mysql storage engines
return "";
}
/**
* The syntax used to add a foreign key constraint to a table.
*
* @param constraintName The FK constraint name.
* @param foreignKey The names of the columns comprising the FK
* @param referencedTable The table referenced by the FK
* @param primaryKey The explicit columns in the referencedTable referenced
* by this FK.
* @param referencesPrimaryKey if false, constraint should be
* explicit about which column names the constraint refers to
*
* @return the "add FK" fragment
*/
public String getAddForeignKeyConstraintString(
String constraintName,
String[] foreignKey,
String referencedTable,
String[] primaryKey,
boolean referencesPrimaryKey) {
StringBuffer res = new StringBuffer( 30 );
res.append( " add constraint " )
.append( constraintName )
.append( " foreign key (" )
.append( StringHelper.join( ", ", foreignKey ) )
.append( ") references " )
.append( referencedTable );
if ( !referencesPrimaryKey ) {
res.append( " (" )
.append( StringHelper.join( ", ", primaryKey ) )
.append( ')' );
}
return res.toString();
}
/**
* The syntax used to add a primary key constraint to a table.
*
* @param constraintName The name of the PK constraint.
* @return The "add PK" fragment
*/
public String getAddPrimaryKeyConstraintString(String constraintName) {
return " add constraint " + constraintName + " primary key ";
}
public boolean hasSelfReferentialForeignKeyBug() {
return false;
}
/**
* The keyword used to specify a nullable column.
*
* @return String
*/
public String getNullColumnString() {
return "";
}
public boolean supportsCommentOn() {
return false;
}
public String getTableComment(String comment) {
return "";
}
public String getColumnComment(String comment) {
return "";
}
public boolean supportsIfExistsBeforeTableName() {
return false;
}
public boolean supportsIfExistsAfterTableName() {
return false;
}
/**
* Does this dialect support column-level check constraints?
*
* @return True if column-level CHECK constraints are supported; false
* otherwise.
*/
public boolean supportsColumnCheck() {
return true;
}
/**
* Does this dialect support table-level check constraints?
*
* @return True if table-level CHECK constraints are supported; false
* otherwise.
*/
public boolean supportsTableCheck() {
return true;
}
public boolean supportsCascadeDelete() {
return true;
}
public boolean supportsNotNullUnique() {
return true;
}
/**
* Completely optional cascading drop clause
*
* @return String
*/
public String getCascadeConstraintsString() {
return "";
}
/**
* Get the separator to use for defining cross joins when translating HQL queries.
* <p/>
* Typically this will be either [<tt> cross join ] or [, ]
* <p/>
* Note that the spaces are important!
*
* @return
*/
public String getCrossJoinSeparator() {
return " cross join ";
}
public ColumnAliasExtractor getColumnAliasExtractor() {
return ColumnAliasExtractor.COLUMN_LABEL_EXTRACTOR;
}
// Informational metadata ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/**
* Does this dialect support empty IN lists?
* <p/>
* For example, is [where XYZ in ()] a supported construct?
*
* @return True if empty in lists are supported; false otherwise.
* @since 3.2
*/
public boolean supportsEmptyInList() {
return true;
}
/**
* Are string comparisons implicitly case insensitive.
* <p/>
* In other words, does [where 'XYZ' = 'xyz'] resolve to true?
*
* @return True if comparisons are case insensitive.
* @since 3.2
*/
public boolean areStringComparisonsCaseInsensitive() {
return false;
}
/**
* Is this dialect known to support what ANSI-SQL terms "row value
* constructor" syntax; sometimes called tuple syntax.
* <p/>
* Basically, does it support syntax like
* "... where (FIRST_NAME, LAST_NAME) = ('Steve', 'Ebersole') ...".
*
* @return True if this SQL dialect is known to support "row value
* constructor" syntax; false otherwise.
* @since 3.2
*/
public boolean supportsRowValueConstructorSyntax() {
// return false here, as most databases do not properly support this construct...
return false;
}
/**
* If the dialect supports {@link #supportsRowValueConstructorSyntax() row values},
* does it offer such support in IN lists as well?
* <p/>
* For example, "... where (FIRST_NAME, LAST_NAME) IN ( (?, ?), (?, ?) ) ..."
*
* @return True if this SQL dialect is known to support "row value
* constructor" syntax in the IN list; false otherwise.
* @since 3.2
*/
public boolean supportsRowValueConstructorSyntaxInInList() {
return false;
}
/**
* Should LOBs (both BLOB and CLOB) be bound using stream operations (i.e.
* {@link java.sql.PreparedStatement#setBinaryStream}).
*
* @return True if BLOBs and CLOBs should be bound using stream operations.
* @since 3.2
*/
public boolean useInputStreamToInsertBlob() {
return true;
}
/**
* Does this dialect support parameters within the <tt>SELECT clause of
* <tt>INSERT ... SELECT ... statements?
*
* @return True if this is supported; false otherwise.
* @since 3.2
*/
public boolean supportsParametersInInsertSelect() {
return true;
}
/**
* Does this dialect require that references to result variables
* (i.e, select expresssion aliases) in an ORDER BY clause be
* replaced by column positions (1-origin) as defined
* by the select clause?
* @return true if result variable references in the ORDER BY
* clause should be replaced by column positions;
* false otherwise.
*/
public boolean replaceResultVariableInOrderByClauseWithPosition() {
return false;
}
/**
* Does this dialect require that parameters appearing in the <tt>SELECT clause be wrapped in cast()
* calls to tell the db parser the expected type.
*
* @return True if select clause parameter must be cast()ed
* @since 3.2
*/
public boolean requiresCastingOfParametersInSelectClause() {
return false;
}
/**
* Does this dialect support asking the result set its positioning
* information on forward only cursors. Specifically, in the case of
* scrolling fetches, Hibernate needs to use
* {@link java.sql.ResultSet#isAfterLast} and
* {@link java.sql.ResultSet#isBeforeFirst}. Certain drivers do not
* allow access to these methods for forward only cursors.
* <p/>
* NOTE : this is highly driver dependent!
*
* @return True if methods like {@link java.sql.ResultSet#isAfterLast} and
* {@link java.sql.ResultSet#isBeforeFirst} are supported for forward
* only cursors; false otherwise.
* @since 3.2
*/
public boolean supportsResultSetPositionQueryMethodsOnForwardOnlyCursor() {
return true;
}
/**
* Does this dialect support definition of cascade delete constraints
* which can cause circular chains?
*
* @return True if circular cascade delete constraints are supported; false
* otherwise.
* @since 3.2
*/
public boolean supportsCircularCascadeDeleteConstraints() {
return true;
}
/**
* Are subselects supported as the left-hand-side (LHS) of
* IN-predicates.
* <p/>
* In other words, is syntax like "... <subquery> IN (1, 2, 3) ..." supported?
*
* @return True if subselects can appear as the LHS of an in-predicate;
* false otherwise.
* @since 3.2
*/
public boolean supportsSubselectAsInPredicateLHS() {
return true;
}
/**
* Expected LOB usage pattern is such that I can perform an insert
* via prepared statement with a parameter binding for a LOB value
* without crazy casting to JDBC driver implementation-specific classes...
* <p/>
* Part of the trickiness here is the fact that this is largely
* driver dependent. For example, Oracle (which is notoriously bad with
* LOB support in their drivers historically) actually does a pretty good
* job with LOB support as of the 10.2.x versions of their drivers...
*
* @return True if normal LOB usage patterns can be used with this driver;
* false if driver-specific hookiness needs to be applied.
* @since 3.2
*/
public boolean supportsExpectedLobUsagePattern() {
return true;
}
/**
* Does the dialect support propagating changes to LOB
* values back to the database? Talking about mutating the
* internal value of the locator as opposed to supplying a new
* locator instance...
* <p/>
* For BLOBs, the internal value might be changed by:
* {@link java.sql.Blob#setBinaryStream},
* {@link java.sql.Blob#setBytes(long, byte[])},
* {@link java.sql.Blob#setBytes(long, byte[], int, int)},
* or {@link java.sql.Blob#truncate(long)}.
* <p/>
* For CLOBs, the internal value might be changed by:
* {@link java.sql.Clob#setAsciiStream(long)},
* {@link java.sql.Clob#setCharacterStream(long)},
* {@link java.sql.Clob#setString(long, String)},
* {@link java.sql.Clob#setString(long, String, int, int)},
* or {@link java.sql.Clob#truncate(long)}.
* <p/>
* NOTE : I do not know the correct answer currently for
* databases which (1) are not part of the cruise control process
* or (2) do not {@link #supportsExpectedLobUsagePattern}.
*
* @return True if the changes are propagated back to the
* database; false otherwise.
* @since 3.2
*/
public boolean supportsLobValueChangePropogation() {
// todo : pretty sure this is the same as the java.sql.DatabaseMetaData.locatorsUpdateCopy method added in JDBC 4, see HHH-6046
return true;
}
/**
* Is it supported to materialize a LOB locator outside the transaction in
* which it was created?
* <p/>
* Again, part of the trickiness here is the fact that this is largely
* driver dependent.
* <p/>
* NOTE: all database I have tested which {@link #supportsExpectedLobUsagePattern()}
* also support the ability to materialize a LOB outside the owning transaction...
*
* @return True if unbounded materialization is supported; false otherwise.
* @since 3.2
*/
public boolean supportsUnboundedLobLocatorMaterialization() {
return true;
}
/**
* Does this dialect support referencing the table being mutated in
* a subquery. The "table being mutated" is the table referenced in
* an UPDATE or a DELETE query. And so can that table then be
* referenced in a subquery of said UPDATE/DELETE query.
* <p/>
* For example, would the following two syntaxes be supported:<ul>
* <li>delete from TABLE_A where ID not in ( select ID from TABLE_A )
* <li>update TABLE_A set NON_ID = 'something' where ID in ( select ID from TABLE_A)
* </ul>
*
* @return True if this dialect allows references the mutating table from
* a subquery.
*/
public boolean supportsSubqueryOnMutatingTable() {
return true;
}
/**
* Does the dialect support an exists statement in the select clause?
*
* @return True if exists checks are allowed in the select clause; false otherwise.
*/
public boolean supportsExistsInSelect() {
return true;
}
/**
* For the underlying database, is READ_COMMITTED isolation implemented by
* forcing readers to wait for write locks to be released?
*
* @return True if writers block readers to achieve READ_COMMITTED; false otherwise.
*/
public boolean doesReadCommittedCauseWritersToBlockReaders() {
return false;
}
/**
* For the underlying database, is REPEATABLE_READ isolation implemented by
* forcing writers to wait for read locks to be released?
*
* @return True if readers block writers to achieve REPEATABLE_READ; false otherwise.
*/
public boolean doesRepeatableReadCauseReadersToBlockWriters() {
return false;
}
/**
* Does this dialect support using a JDBC bind parameter as an argument
* to a function or procedure call?
*
* @return True if the database supports accepting bind params as args; false otherwise.
*/
public boolean supportsBindAsCallableArgument() {
return true;
}
/**
* Does this dialect support `count(a,b)`?
*
* @return True if the database supports counting tuples; false otherwise.
*/
public boolean supportsTupleCounts() {
return false;
}
/**
* Does this dialect support `count(distinct a,b)`?
*
* @return True if the database supports counting distinct tuples; false otherwise.
*/
public boolean supportsTupleDistinctCounts() {
// oddly most database in fact seem to, so true is the default.
return true;
}
}
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