NOT IN doesnt work as expected!!

Question

Hi
I need to count data in a table after comparing the values from another table. Following are the details of the test tables that worked fine and the result was the expected one.
DESC A
Name Null? Type
ID VARCHAR2(10)
DESC B
Name Null? Type
ORGID VARCHAR2(10)
select * from a;
ID
1I
2I
3I
4I
select * from b;
ORGID
1I
2
SELECT COUNT(*) FROM A WHERE ID NOT IN (SELECT ORGID FROM B);
COUNT(*)
3
So far so good. Here is my problem
desc org
Name Null? Type
ORGID VARCHAR2(100)
desc newintlorgs
Name Null? Type
ID VARCHAR2(100)
SELECT DISTINCT ORGID FROM ORG WHERE ORGID LIKE '9258%';
ORGID
9258
92580
92581
select distinct id from newintlorgs where id like '9258%';
ID
9258I
select count(*) from newintlorgs where id not in (select orgid from org);
COUNT(*)
0
It should show atleast 1 record ie 9258I since it is not present in ORG table but present in NEWINTLORGS table but the count shows 0 record.
Any ideas why it is not showing?
thanks in advance

Answer 1

Probably you have NULL values in your ORG table.
From the documentation:
»If any item in the list following a NOT IN operation evaluates to null, then all rows evaluate to FALSE or UNKNOWN, and no rows are returned.«
So you need to add a »where not null« condition:
michaels>  with org as
(select cast('9258' as varchar2(100)) orgid from dual union all
select '92580' orgid from dual union all
select '92581' orgid from dual union all
select null orgid from dual
newintlorgs as
select cast('9258I' as varchar2(100)) id from dual
select count(*) from newintlorgs where id not in (select orgid from org where orgid is not null)
  COUNT(*)
         1Alternativly you can use the NOT EXISTS condition.