Returns a string containing the last SQLSTATE, or NULL if no error has occurred.
If a link resource is passed to ingres_errsqlstate() it returns the last error recorded for the link. If no link is passed then ingres_errsqlstate() returns the last error reported using the default link.
The function, ingres_errsqlstate(), should always be called after executing any database query. Calling another function before ingres_errsqlstate() is called will reset or change any error message from the last Ingres function call.
See also ingres_errno() and ingres_errsqlstate().