i'm using firebird 1.02
i got this table "salesOrder"
and field
salesOrderNo(integer),custid(integer),transdate(date),lostsales(varchar 256)

with this sql statement
select * from salesorder where lostsales ='YES'
i can get my result

but when i used this sql statement
select * from salesorder where lostsales <>'YES'

then i receive no record from the tables.
i 'm very sure that there is records with field (lostsales ) as null.

why is it so???
anyone got this similar problem??