Returns the error text from the last MySQL function, or '' (the empty string) if no error occurred.
Errors coming back from the MySQL database backend no longer issue warnings. Instead, use mysql_error() to retrieve the error text. Note that this function only returns the error text from the most recently executed MySQL function (not including mysql_error() and mysql_errno()), so if you want to use it, make sure you check the value before calling another MySQL function.
Note: If the optional argument is specified the given link is used to retrieve the error message. If not, the last opened link is used.
See also: mysql_errno()