PHP:MySQL what if we don't close the opened connections

Question

In PHP + MySQL

This is:

$conn = mysql_connect("server","user","pass");
mysql_select_db("datbasename");

what we do to open a connection.

And this is:

mysql_close($conn);

what we do to close the connection.

• WHAT if we don't close the connections? What are going to be the effects?
• After what CONDITION the opened connections are automatically closed?

Answer 1

From the PHP documentation for mysql_close :

Using mysql_close() isn't usually necessary, as non-persistent open links are automatically closed at the end of the script's execution. See also freeing resources.

Answer 2

With mysql_connect connection will close, when script is ended.

mysql_pconnect doesn't close connection.

If you work with more then 1 mysql servers, is necessery to control your closing connections, or create some persistance.

Answer 3

In a small application nothing at all. PHP is nice and cleans up memory/closes connections upon scripts execution completion. If you are concerned about resources and utilization then I suggest closing your connections when you are finished using them.