Submitted by: @reevespaul

The behaviour of this function seems to have changed slightly.

In FB 2.5 this string:

SELECT * FROM DEPT_BUDGET(0)

will execute in isc_dsql_execute_immediate without error.

If the server is FB 3.0 and the client is Fb 2.5 this error is thrown:

Dynamic SQL Error
-SQLDA missing or incorrect version, or incorrect number/type of
variables
-unknown ISC error 336003111

If the server is Fb 3.0 and the client is Fb 3.0 this error is thrown:

Dynamic SQL Error
-SQLDA error
-Wrong number of parameters (expected 1, got 0)

In all cases isc_dsql_execute_immediate is called with a null xsqlda.

I've tested this with a control statement that does a dummy update. In
all those cases execution succeeds correctly with a null xsqlda.

Obviously select statements are not meant to work with
isc_dsql_execute_immediate. And it is arguable that the old behaviour
was incorrect because it allowed misuse of the function. However, if we
are going to throw an error I think it should be more explicit. Perhaps
something along the lines of:

'Select statements cannot be execute by isc_dsql_execute_immediate'

Commits: 641a2b9 6b4a5c9

====== Test Details ======

Can`t reproduce using neither ISQL nor Python: they both prevent from API misuse.