I saw this “SQL joins as Venn diagrams” image on this Twitter page. To give attribution to the original author, it appears to have been created by C.L. Moffatt and documented in this Visual Representation of SQL Joins article. However, this article makes the case that Venn diagrams are not an accurate description of SQL joins.
As a quick note today, here’s an example Play Framework Anorm SQL SELECT query that queries for a single value:
I don’t have time to write about ScalikeJdbc right now, so I’ll just say that it’s been working well for me. Here’s one of the first test examples I created, a simple SQL SELECT query that prints some output from a database table:
As a brief note to self, I just used this SQL SELECT query to show both (a) master/summary information about each URL row in the
urls database table, and also (b) detail information in the form of the number of rows in the
url_clicks database table for each row in the
As a quick note to self, one way to implement paging in a Play Framework application is to use the
offset arguments in a MySQL query. This way you can show X number of objects on one web page, then give the user Next and Previous links so they can scroll backwards and forwards through the dataset.
To implement paging with a MySQL query, use the
offset query parameters, as shown in this example:
In general the online Play Framework documentation is excellent, but one area where I needed more help was in seeing more examples of the Anorm syntax. To that end, here are some Anorm query examples, taken from a Play Framework application I worked on recently. But first, a little background about Anorm.
It’s embarrassing how long it took to get this to work, but if you ever need to select a single row from a database using Play Framework (version 2.6), Anorm, and
singleOpt, I hope this example is helpful, and will save you time and frustration:
Here’s a cool tip: if you want to search for a text string in all fields of all tables of a MySQL database, you can use phpMyAdmin to do this very easily. Here are the steps to search every MySQL/MariaDB database table.
1) Select the desired database
The first step is to select the database you want to search. Don’t select a table — just select the database you want to search. (If you select a table you’ll get a different search form in Step 2.)
I’m not going to comment on the following code too much or provide support for it, but (a) if you need to create an XML Sitemap for a Drupal 8 website, and (b) you don’t like the Drupal 8 sitemap modules that are available, then (c) this PHP script can serve as a starting point for you.