That's it.
Thanks a lot to Ivan.

But why does gpre map LIKE to something it shouldn't do?
Possibly I surveyed some important documents.

Best regards to all
Firebird supporters

> > EXEC SQL DECLARE IT40_CURSOR CURSOR FOR
> > SELECT NAMEKLASSE, ...
> > WHERE
> > BEZ_STD LIKE :it40_bez_std
> ...
>
> That is what I thought, your commands are not the same.
> If you try in IBOconsole this command
>
> select nameklasse,
> kategorie,

...

> where

... bez_std like 'LEHR%%' || ''

> and (namediff is null OR namediff <> 'XXX')
> order by bez_std;
>
> you should get equally bad performance as with gpre version.
> (because now LIKE operator also will not be able to use index).
>
> If you need wildcards only at the end of pattern in LIKE,
> use STARTING clause instead.
>
> Ivan