separate queries of SQL functions?

Question

I am using a combination of php and MySql. My case is I am using two queries (one 'select' and 'insert') for an activity, sometimes 3 queries. This will be done very frequently by different users.

I am using mysql_query function separately to execute the queries. Is this good or is it better to use a SQL function which executes all the queries. I want to know which is better regarding performance.

Answer 1

In my opinion it is better practice to create a function which performs a single operation well. This makes the functions easier to test and allows them to be utilized in other operations in the future. In your case I would create a stored procedure to execute the routine.

Answer 2

If you're using the mysqli extension you can utilize multi_query :

http://php.net/manual/en/mysqli.multi-query.php

However please note that if one of the queries relies on the success of another of the queries, they should be separated out for error checking.

Answer 3

It would help if you could show concrete examples - right now, it's all very hypothetical. However:

If you can combine the operations into a single query, it's the fastest option. For instance:

insert into tableA
select x, y, z
from tableB
where Foo = Bar

If you have to do some processing on the results of the select statement, you can create a stored procedure to do the processing. This avoids the round trip of sending the data back to your PHP server, which should yield a performance benefit - however, it may well be that PHP is a better/faster language to execute the processing in than the stored procedure. For instance, if you have to manipulate text, I'd do it in PHP.