Future requests for a connection with the same dsn, user, password combination (via odbc_connect() and odbc_pconnect()) can reuse the persistent connection.
Returns an ODBC connection id or 0 (FALSE) on error. This function is much like odbc_connect(), except that the connection is not really closed when the script has finished. Future requests for a connection with the same dsn, user, password combination (via odbc_connect() and odbc_pconnect()) can reuse the persistent connection.