int sybase_pconnect (string servername, string username, string password)
Returns: A positive Sybase persistent link identifier on success, or false on error
sybase_pconnect() acts very much like sybase_connect() with two major differences.
First, when connecting, the function would first try to find a (persistent) link that's already open with the same host, username and password. If one is found, an identifier for it will be returned instead of opening a new connection.
Second, the connection to the SQL server will not be closed when the execution of the script ends. Instead, the link will remain open for future use (sybase_close() will not close links established by sybase_pconnect()).
This type of links is therefore called 'persistent'.