IATA member airlines are required to interline, so there is no need for such a database. Airlines choose to supplement this mandatory interlining with their own agreements (e.g. JQ with AF). Separate tickets are just that -- so no interlining applies; but many airlines will do interlining as a service, sometimes just within an alliance or by FF status. Finally some airlines choose not to join IATA precisely to avoid interlining, however some LCCs are now moving up and offering more service (e.g. JetBlue).