On the SitePoint PHP blog Zach Wallace shares more database wisdom with his readers introducing three more JOINs you should know in your development work.
There are many ways to JOIN data from two database tables and filter the information you require. Craig Buckler wrote a popular piece on understanding JOINs; namely INNER, LEFT, RIGHT, and FULL OUTER. This article is an extension of that one.
He starts with the data he'll be working with: customers and books, linked by a
book_id column. He then quickly reviews some of the joins already discussed in the previous article (LEFT, RIGHT, OUTER, INNER) before getting into the newer, more powerful types:
- LEFT JOIN with Exclusion
- RIGHT JOIN with Exclusion
- OUTER JOIN with Exclusions
He finishes the post with a few other thoughts about using WHERE clauses in JOINs, the CROSS JOIN and how the JOINs relate to each other in MySQL.