NULL vs string comparison in Informix 9.3

[jkol]

We are trying to migrate from Informix 7.x to 9.3 and found one issue with our existing sql code.

Following sql code retrieves multiple rows from the database in 7.x

select tabname from systables
where tabid in
(select tabid from syssyntable
where owner != "informix" and dbname != "ppcdds023&quot

whereas the same code retrieves no rows in 9.3 with the same table entries.

Currently the value of dbname in syssyntable is null in our database.
Should the above yield the same results in 9.3 also since "ppcdds023" is not equal to null??

 

[vpshriyan]

Hi,

First check for the number of rows returned by the inner sql statement:

select tabid from syssyntable
where owner != "informix" and dbname != "ppcdds023" ;

If it does not you know the obvious; sub-query is not sending any row to the first (outer) select statement.

Regards,
Shriyan