Re: Inconsistent Query Results
Date: 1 Jul 2003 13:42:17 -0700
Message-ID: <f0f51c80.0307011242.488a8af6_at_posting.google.com>
LKBrwn_DBA <member30625_at_dbforums.com> wrote in message news:<3054222.1056815889_at_dbforums.com>...
> ABOUT NULLS
> to: sybrandb
>
> "When an indexed column is NULL, or when all columns in a
> concatenated index are NULL, then the row concerned will NOT have an
> entry in the index"
>
> Quote from:
> Oracle SQL High-Performance Tuning
> Second Edition
> Page 120, paragraph 8 "NULL VALUES"
> Author:Guy Harrison
> (c) 2001 - Prentice Hall PTR
That's true, but it's not going to affect a query that uses the index. If a query is using the index, then it's only going to search for rows that have a value, since to use the index there will need to be a where clause on that column.
In the end, the presence of nulls in a column is NOT going to affect the results that are returned, whether or not the column is indexed.
The statement "NULLs in any OS_NAME will produce invalid results in your query." is inaccurate.
Adam Ruth Received on Tue Jul 01 2003 - 22:42:17 CEST