Wednesday, October 22, 2014

When MySQL joins become disjointed

I honestly don't know how I've managed to avoid this until now, but I ran into an issue today where I could not get a SQL query with a join to execute properly.  I kept getting errors saying that I had referenced an unknown column.  After rewriting the query several times and questioning my sanity, I decided to do a quick search online.  Much to my surprise, I quickly found the answer.  The way joins are handled changed ever so slightly in MySQL 5.0, such that they are now more closely aligned with ANSI SQL standards.  By tweaking the query and adding parentheses in the from clause, all worked perfectly.

Many thanks to jbrinkmann for his excellent article on the subject at MySQLjoin.com.

No comments:

Post a Comment