SQL Delete query non-functional

Question

I found some duplicate records in my database table called Dwg_Register. Now I am running the following query to delete them.

Delete FROM PIMS.dbo.Dwg_Register WHERE Dwg_Ref = 'NULL' AND Title = 'NULL' AND [Status] = 'Approved As Noted'

I can clearly see that there are 16 duplicate records found in the table having these fields mentioned in the above query repeating ... but when I execute this command in SQL server .. successfully executes but result is (0) records effected.

Can someone pls explain what is actually goin on in SQL server.

Thank you.

Don't use `='NULL'`, use `Dwg_Ref is null`, etc. The way you have it written it looks like you have a string value of `'null'`. — Taryn, Aug 29 '13 at 10:29
possible duplicate of [SQL is null and = null](http://stackoverflow.com/questions/9581745/sql-is-null-and-null) — Taryn, Aug 29 '13 at 10:32

score 3 · Accepted Answer · answered Aug 29 '13 at 10:28

3

Try:

DELETE FROM PIMS.dbo.Dwg_Register
WHERE Dwg_Ref IS NULL
AND Title IS NULL
AND [Status] = 'Approved As Noted'

When selecting NULL values in SQL you must use IS NULL instead of = 'NULL'

answered Aug 29 '13 at 10:28

Lewis

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8
20

score 0 · Answer 2 · answered Aug 29 '13 at 10:33

0

Use IS NULL instead of = 'NULL'

= 'NULL' will try to match with string NULL

answered Aug 29 '13 at 10:33

Abhishek Singh

10,243
22
74
108

Very well explained. Thanks – Aug 29 '13 at 11:24

SQL Delete query non-functional

2 Answers2