说明

Open a persistent connection to an Ingres database.

There are only two differences between this function and ingres_connect(): First, when connecting, the function will initially try to find a (persistent) link that is already opened with the same parameters. If one is found, an identifier for it will be returned instead of opening a new connection. Second, the connection to the Ingres server will not be closed when the execution of the script ends. Instead, the link will remain open for future use (ingres_close() will not close links established by ingres_pconnect()). This type of link is therefore called "persistent".