SQL Not Like Statement not working

Question

I have the following code within a stored procedure.

WHERE
    WPP.ACCEPTED = 1 AND
    WPI.EMAIL LIKE '%@MATH.UCLA.EDU%' AND
    (WPP.SPEAKER = 0 OR
    WPP.SPEAKER IS NULL) AND
    WPP.COMMENT NOT LIKE '%CORE%' AND
    WPP.PROGRAMCODE = 'cmaws3'

The NOT LIKE statement is not working, and yes before anyone says anything there are items with the COMMENT column that does not include CORE and all the other columns are ok.

Does anyone know what is wrong with this?

Answer 1

If WPP.COMMENT contains NULL, the condition will not match.

This query:

SELECT  1
WHERE   NULL NOT LIKE '%test%'

will return nothing.

On a NULL column, both LIKE and NOT LIKE against any search string will return NULL.

Could you please post relevant values of a row which in your opinion should be returned but it isn't?

Answer 2

Just come across this, the answer is simple, use ISNULL. SQL won't return rows if the field you are testing has no value (in some of the records) when doing a text comparison search, eg:

WHERE wpp.comment NOT LIKE '%CORE%'

So, you have temporarily substitute a value in the null (empty) records by using the ISNULL command, eg

WHERE (ISNULL(wpp.comment,'')) NOT LIKE '%CORE%'

This will then show all your records that have nulls and omit any that have your matching criteria. If you wanted, you could put something in the commas to help you remember, eg

WHERE (ISNULL(wpp.comment,'some_records_have_no_value')) NOT LIKE '%CORE%'

Answer 3

Is the value of your particular COMMENT column null?

Sometimes NOT LIKE doesn't know how to behave properly around nulls.

Answer 4

I just came across the same issue, and solved it, but not before I found this post. And seeing as your question wasn't really answered, here's my solution (which will hopefully work for you, or anyone else searching for the same thing I did;

Instead of;

... AND WPP.COMMENT NOT LIKE '%CORE%' ...

Try;

... AND NOT WPP.COMMENT LIKE '%CORE%' ...

Basically moving the "NOT" the other side of the field I was evaluating worked for me.

Answer 5

mattgcon,

Should work, do you get more rows if you run the same SQL with the "NOT LIKE" line commented out? If not, check the data. I know you mentioned in your question, but check that the actual SQL statement is using that clause. The other answers with NULL are also a good idea.