Today, mysql_real_escape_string() is escaping single quotes AND double quotes.

Question

$str = 'BEGIN This is a "quote" test. \'Single\' END';
echo $str . "\n";
echo mysql_real_escape_string($str);

// Outputs:
BEGIN This is a "quote" test. 'Single' END
BEGIN This is a \"quote\" test. \'Single\' END

Running PHP 5.3.2 on CentOS. As far as I can remember, mysql_real_escape_string() will only escape single quotes to prevent sql injections. Double quotes have nothing to do with that, because " does not start or end a string literal in MySQL!

This is causing backslashes to get inserted into the data! Something I clearly do not want.

Answer 1

" does start a string in MySQL. (See: Strings)

Exception:

If the ANSI_QUOTES SQL mode is enabled, string literals can be quoted only within single quotation marks because a string quoted within double quotation marks is interpreted as an identifier.

Answer 2

Sounds like magic quotes got turned on.

This post details your problem exactly, along with fixes. http://www.sitepoint.com/forums/showthread.php?t=545824