Mysql_connect() is used to open a new connection to the database, while mysql_pconnect() is used to open a persistent connection to the database. It specifies that each time the page is loaded, mysql_pconnect() does not open the database.

mysql_connect and mysql_pconnect are both functions used to establish a connection to a MySQL database in PHP, but they differ in their behavior:

mysql_connect: This function establishes a regular, non-persistent connection to the MySQL database server. Each time mysql_connect is called, a new connection to the database server is created. After the script finishes executing, the connection is closed automatically.
mysql_pconnect: This function establishes a persistent connection to the MySQL database server. Unlike mysql_connect, mysql_pconnect will try to reuse an existing connection with the same connection parameters, if one exists. If no connection exists, it will create one. Persistent connections are not closed automatically when the script finishes executing; instead, they are left open and can be reused by subsequent scripts that request a connection with the same parameters.

In summary, the main difference between mysql_connect and mysql_pconnect is that mysql_pconnect uses persistent connections, which can potentially improve performance by reducing the overhead of establishing a new connection for each script execution. However, it’s essential to be cautious with persistent connections as they can lead to resource exhaustion if not managed properly, especially in high-traffic environments. Additionally, the mysql_ functions are deprecated in PHP and have been replaced by newer extensions like mysqli or PDO for interacting with MySQL databases.