Does unique key allow more than one null value's

lal_arun_272 · New User Joined: 09 Oct 2006 Posts: 31 Location: Bangalore

Hi

If we defined one of table column as unique key. Does this column allow more than one null value's in that ??.

I got confused with below points ..in "In DB2 null is not equle to null"

So does it unique can have more than one null value's ??

Please help me to understand this

Thanks
Arunlal

paresh.ojha · New User Joined: 21 Sep 2006 Posts: 17

NULL value means the value is undefined. NULL is not eqal to anything even NULL != NULL. So if you have any field in a table with NULL value you cant select the row with SELECT * FROM TBLNAME where FIELD = NULL rather than it should be SELECT * FROM TBLNAME WHERE FIELD IS NULL.

Hope this will help you.