Cao Ancoinc wrote:

> Hi All
> It seems that I have an index problem

It would be easier for us to guess what the problem is
if you supplied the details of all indexes on the table,
the query plan generated, and the data types of the
three fields.

>
> Select * from Ostrip where DepotId='23' and InvNo='5016308' returns null

As an aside, a query that returns no rows is different from a query
which return null results. In relational databases, null has a specific
meaning which is different from no data.

Other questions.

1) Are all the queries run from the same transaction?
2) Are the results consistent?
3) Have you tried dropping the index(es)?
4) Have you tried rebuilding the index(es)?
5) What version of Firebird are you running
6) Superserver or classic?
7) What operating system and version?


Regards,


Ann