我只是坚持mysql_ *函数用于简单的mysql_num_rows（），并使用PDO进行更大的查询？

Question

I am converting all my queries to PDO but I am wondering if I should leave "simple" queries as mysql_* functions, like this one:

echo mysql_num_rows(mysql_query("SELECT id FROM users WHERE user_id='$user_id'"))

What I mean is that it just takes one line of code, where as if I use PDO, it would take 4 lines to write. The sole purpose of this query is to count the rows and echo the result.

Should I stick to mysql_* for that kind of small query? Also, note that in my script, there are 10 other queries like this one.

Thanks in advance

Answer 1

Personally I'd convert them all. The main reason I say that is because you will have 2 connections to the DB server for each request. 1 for the old mysql_ functions and 1 for PDO. Not a huge deal but if your site is/gets very large, its just more memory and overhead which you don't need. If you get overloaded, instead of having say 500 connections to the MySQL server, you have now raised this to 1000 which means more memory and more threads and pushes you closer to your resource limits when it is unnecessary.

I can also see the potential for future developers other than yourself seeing the usage of both and not understanding the reasoning for using one or the other in a particular case. This may not be an issue though if the code is and always will be yours to manage.