“set names” vs mysqli_set_charset — besides affecting mysqli_escape_string, are they identical?

Question

It seems to be common knowledge to use mysql_set_charset / mysqli::set_charset instead of the direct MySQL query set names.

The reason often cited is that se

Answer 1

SET NAMES ... is a convenience alias:

A SET NAMES 'charset_name' statement is equivalent to these three statements:

SET character_set_client = charset_name;
SET character_set_results = charset_name;
SET character_set_connection = charset_name;

Setting character_set_connection to charset_name also implicitly sets collation_connection to the default collation for charset_name.

... that provides MySQL Server with all the text-encoding information required for current connection. So far so good.

But PHP is also involved and it will not learn anything from here because it's basically a random user query. There are two things that PHP will not do for obvious performance reasons:

• Scan all user queries sent to the server to detect calls to SET NAMES.
• Ask MySQL for current values of the involved directives every time something needs to be done.

In short: this method notifies the server but not the client. However, dedicated PHP functions do both things.