Mysql_close() cannot be used to close the persistent connection. However, it can be used to close a connection opened by mysql_connect().

In MySQL, the mysql_close() function is used to close the connection to the MySQL server that was previously opened with mysql_connect() or mysql_pconnect() functions. When you no longer need to access the database, it’s good practice to close the connection to free up system resources and avoid leaving connections open unnecessarily, especially in environments with a limited number of connections allowed. This helps optimize the performance and scalability of your application.