(PHP 3, PHP 4 )
Returns 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.
注: If the optional argument is specified the given link is used to retrieve the error code. If not, the last opened link is used.
See also: mysql_error()