Solved

Testing if bit field = 1

Posted on 2004-04-26
5
341 Views
Last Modified: 2012-08-13
I have a field 'del' in a table, 'mytable',  defined as type 'bit'. It is also nullable. I have two rows, one with del=1, and one with del=NULL. In my select statement I have


select * from mytable
where del<>1

but I am returned no rows. Can i test a bit field this way?

thx

Rich
0
Comment
Question by:RichardFox
  • 3
  • 2
5 Comments
 

Author Comment

by:RichardFox
ID: 10919739
Oh, and if I use

select * from mytable
where del=1

the row is returned. So del=1 appears to work but del<>1 doesn't
0
 

Author Comment

by:RichardFox
ID: 10920020
And a little bit more (excuse the pun):

If a row has del set to zero,

select * from mytable
where del<>1

returns the row. BUT, it does not return rows where del is NULL! Why? Definitely NULL is <> 1!
0
 
LVL 34

Expert Comment

by:arbert
ID: 10920050
This is how null works--straight from books online:

Care must be taken when comparing null values. The behavior of the comparison depends on the setting of the SET ANSI_NULLS option.

When SET ANSI_NULLS is ON, a comparison in which one or more of the expressions is NULL does not yield either TRUE or FALSE; it yields UNKNOWN. This is because a value that is unknown cannot be compared logically against any other value. This occurs if either an expression is compared to the literal NULL, or if two expressions are compared and one of them evaluates to NULL. For example, this comparison always yields UNKNOWN when ANSI_NULLS is ON:
0
 
LVL 34

Accepted Solution

by:
arbert earned 50 total points
ID: 10920055

select * from mytable
where del<>1 or del is null
0
 

Author Comment

by:RichardFox
ID: 10920103
Thanks for the education, I appreciate it
0

Featured Post

Optimizing Cloud Backup for Low Bandwidth

With cloud storage prices going down a growing number of SMBs start to use it for backup storage. Unfortunately, business data volume rarely fits the average Internet speed. This article provides an overview of main Internet speed challenges and reveals backup best practices.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

The Delta outage: 650 cancelled flights, more than 1200 delayed flights, thousands of frustrated customers, tens of millions of dollars in damages – plus untold reputational damage to one of the world’s most trusted airlines. All due to a catastroph…
Ever wondered why sometimes your SQL Server is slow or unresponsive with connections spiking up but by the time you go in, all is well? The following article will show you how to install and configure a SQL job that will send you email alerts includ…
Via a live example combined with referencing Books Online, show some of the information that can be extracted from the Catalog Views in SQL Server.
Viewers will learn how to use the SELECT statement in SQL and will be exposed to the many uses the SELECT statement has.

829 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question