JPA Association Fetching Validator
Introduction In this article, I’m going to show you how we can build a JPA Association Fetching Validator that asserts whether JPA and Hibernate associations are fetched using joins or secondary queries. While Hibernate does not provide built-in support for checking the entity association fetching behavior programmatically, the API is very flexible and allows us to customize it so that we can achieve this non-trivial requirement.
SQL CROSS APPLY – A Beginner’s Guide
Introduction In this article, we are going to see how the SQL CROSS APPLY works and how we can use it to cross-reference rows from a subquery with rows in the outer table and build compound result sets. CROSS APPLY is basically equivalent to the LATERAL JOIN, and it’s been supported by SQL Server since version 2005 and Oracle since version 12c.
Merge Join Algorithm
Introduction In this article, we are going to see how the Merge Join Algorithm, also known as Sort-Merge Join, works and when it’s suitable for a relational database system to employ it in order to execute an SQL JOIN query.
Hash Join Algorithm
Introduction In this article, we are going to see how the Hash Join Algorithm works and when it’s suitable for a relational database system to employ it in order to execute an SQL JOIN query.
Nested Loop Join Algorithm
Introduction In this article, we are going to see how the Nested Loop Join Algorithm works and when it’s suitable for a relational database system to employ it in order to execute an SQL JOIN query.
SQL LATERAL JOIN – A Beginner’s Guide
Introduction In this article, we are going to see how the SQL LATERAL JOIN works, and how we can use it to cross-reference rows from a subquery with rows in the outer table and build compound result sets. A LATERAL JOIN can be used either explicitly, as we will see in this article, or implicitly as it’s the case for the MySQL JSON_TABLE function.
SQL JOIN USING – A Beginner’s Guide
Introduction In this article, we are going to see how the JOIN USING clause works in SQL, and how we can use it to replace the ON condition clause when the columns used to join the two tables have the same name in both the parent and the child tables.
SQL LEFT JOIN – A Beginner’s Guide
Introduction In this article, we are going to see how LEFT JOIN works in SQL, and how we can use it to associate rows belonging to different tables and build compound result sets. Unlike JOIN or INNER JOIN, LEFT JOIN is an OUTER JOIN. So, LEFT JOIN and LEFT OUTER JOIN are equivalent. Other OUTER JOIN types are RIGHT OUTER JOIN and FULL OUTER JOIN. However, since the SQL OUTER keyword is superfluous, it’s usually omitted.
SQL INNER JOIN – A Beginner’s Guide
Introduction In this article, we are going to see how INNER JOIN works in SQL, and how we can use it to associate rows belonging to different tables and build compound result sets.
