using preg_replace to add backslash before single quote

How to add a backslash before single quotes using preg_replace() php functio开发者_JS百科n ?

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In case you are not trying to escape Database input:

$string = str_replace("'", "\\'", $string);

In case you are:

Please consider using the appropriate escaping function. (E.g. mysql_real_escape_string) or just use prepared statements.

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just use the function str_replace to replace every instance of ' to \'