Found a strange thing with NULL..
There is a table with not null field.
select count(*) from table where field is null
returns 0 rows.
select field from table where PK=XXX
returns:
(null)

the same from embedded sql, indicator variable == 0, but the field contains "(null)", and has a length 6.....

DB21085I Instance "db2inst1" uses "32" bits and DB2 code release "SQL08014"
with level identifier "02050106".
Informational tokens are "DB2 v8.1.0.40", "n040122", "MI00075", and FixPak "4".
Product is installed at "/opt/IBM/db2/V8.1".

Linux.

select count(*) from table where field='(null)' returns a lot....
Seems it's my buggy web developer.... I think it is he has inserted, or his fu$%ing application. There are a lot of rows with '(null)' inserted as a string on the field....