(PHP 3, PHP 4 )
mysql_errno -- Returns the numerical value of the error message from previous MySQL operationReturns the error number from the last MySQL function, or 0 (zero) if no error occurred.
Errors coming back from the MySQL database backend no longer issue warnings. Instead, use mysql_errno() to retrieve the error code. Note that this function only returns the error code 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.
See also: mysql_error()