Warning: mysql_free_result (): _ PHP Tutorial

Warning: mysql_free_result ():. Our website prompts the following error: Warning: mysql_free_result (): the parameter of mysql_free_result is incorrect. However, our website prompts the following error: Warning: mysql_free_result (): supplied argument is not a valid MySQL result resource

There are three situations:

The parameter mysql_free_result is invalid.
The mysql_query result may be empty.
Check whether no result is output.

Using mysql_free_result (): supplied argument is not a valid MySQL result resource. There are three situations: the mysql_free_result parameter is incorrect...