jdbc

Scala: Popular tools, libraries, and frameworks

Table of Contents1 - Build tools2 - Testing tools3 - Database4 - Functional Programming5 - Asynchronous/parallel/concurrent programming6 - Web frameworks7 - JSON8 - HTTP clients9 - Configuration/properties10 - Many more

This page is a collection of popular tools, libraries, and frameworks for the Scala programming language.

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Build tools

A Scala JDBC select and insert example (showing Statement, ResultSet, and PreparedStatement)

Here’s an example of how to connect to a JDBC database with Scala. I have no idea why I got into the try/catch/finally details in a trivial little example like this, but if you want to see how to connect to a database with JDBC and query that database with a JDBC Statement (which yields a ResultSet), I hope this example is a little helpful:

A ScalikeJdbc SQL SELECT example that maps results to a list of case class instances

Here’s another ScalikeJdbc example. The main benefits of this example are:

  • It shows how to perform a SQL SELECT with ScalikeJdbc
  • How to map the ResultSet values to create a series of objects from the ResultSet
  • How to connect to a database with ScalikeJdbc using a JDBC style of connecting (as opposed to putting the JDBC parameters in a configuration file)

Here’s the ScalikeJdbc example code:

A ScalikeJdbc SQL UPDATE syntax example

Here’s an example of how to write a SQL UPDATE query with ScalikeJdbc:

def updateUrlClickGeoInfo(urlClickId: Long, gi: GeoInfo): Int = NamedDB('kbhr) localTx { implicit session =>
    sql"""
    update url_clicks
    set city = ${gi.city}, state = ${gi.state}, country = ${gi.country}
    where id = ${urlClickId}
    """.update.apply()
}

(As a note to self, this code comes from my PopulateKbhrGeo1 app.)

A ScalikeJdbc SQL SELECT example with WrappedResultSet

Here’s another Scala ScalikeJdbc SQL SELECT example. A few unique things about this example is that it shows the JDBC-style parameters; it shows how to use a case class and the “service” style approach; and it shows how to use the WrappedResultSet as shown. Here’s the code:

Play Framework: An SBT build.sbt file for JDBC, MySQL, and Anorm

As a note to self, if you want to use JDBC, MySQL, and Anorm with the Play Framework 2.6, you’ll need a libraryDependencies entry like this in your SBT build.sbt file:

libraryDependencies ++= Seq(
    guice,
    "org.scalatestplus.play" %% "scalatestplus-play" % "3.1.2" % Test,
    jdbc,
    "mysql" % "mysql-connector-java" % "5.1.46",
    "com.typesafe.play" %% "anorm" % "2.5.3"
)

 

How to read from two databases at the same time with ScalikeJdbc

This example shows how to connect-to and read-from multiple databases with ScalikeJdbc (a Scala JDBC library). I assume you already know how to use ScalikeJdbc with one database, so I’m only going to show the code and configuration file. (I’m not going to explain the details.)

The ScalikeJdbc configuration file

My ScalikeJdbc code is in an SBT project, so the ScalikeJdbc configuration file is at src/main/resources/application.conf:

How to speed up JDBC PreparedStatement MySQL batch inserts

If you ever need to batch-insert a lot of records into a MySQL/MariaDB database using the JDBC PreparedStatement (as in preparedStatement.executeBatch()) be sure to change the MySQL URL to use the rewriteBatchedStatements, as shown here:

"jdbc:mysql://localhost:8889/DATABASE?rewriteBatchedStatements=true"

For a recent project I needed to batch-insert about eleven million records into a MySQL database, and the runtime was about 55 minutes. Once I added rewriteBatchedStatements=true to the MySQL URL, the batch-insert time was reduced down to only three minutes. That one little change made all the difference.