RE: IN ignore null values
- From: "Niall Litchfield" <n-litchfield@xxxxxxxxxxxxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 20 Feb 2004 14:47:09 +0000
In the first case you are testing for equality against NULL.=20
Niall Litchfield
Oracle DBA
Audit Commission
+44 117 975 7805=20
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> Subject: IN ignore null values=20
>=20
>=20
> An interesting observation
>=20
> IN ignore null values as you can see in the table there are=20
> 310 null values
> in column TBL_DSM.
>=20
> SQL> select count(*) from daz.utl_tablas_me
>=20
> 2 where tbl_dsm in
>=20
> 3 (select null from daz.utl_tablas_me);
>=20
> COUNT(*)
>=20
> ---------
>=20
> 0
>=20
> SQL> select count(*) from daz.utl_tablas_me
>=20
> 2 where exists(select null from daz.utl_tablas_me);
>=20
> COUNT(*)
>=20
> ---------
>=20
> 310
>=20
>=20
>=20
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>=20
>=20
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