Should I use one big SQL Select statement or several small ones?

Question

I\'m building a PHP page with data sent from MySQL.

Is it better to have

• 1 SELECT query with 4 table joins, or
• 4 small SELE

Answer 1

It might depend on what you do with the data after you fetch it from the DB. If you use each of the four results independently, then it would be more logical and clear to have four separate SELECT statements. On the other hand, if you use all the data together, like to create a unified row in a table or something, then I would go with the single SELECT and JOINs.

I've done a bit of PHP/MySQL work, and I find that even for queries on huge tables with tons of JOINs, the database is pretty good at optimizing - if you have smart indexes. So if you are serious about performance, start reading up on query optimization and indexing.