Why select 'abc' + null =null

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SQL

Hello Friends,

I would like to know that why select 'abc' + null results in null.

Thanks,
Jagjot

Posted 1-Feb-11 1:06am

Jagjot Singh

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Prerak Patel · Accepted Answer · 2011-02-01T01:10:00

Solution 1

You can switch it off.

SET CONCAT_NULL_YIELDS_NULL { ON | OFF }

http://msdn.microsoft.com/en-us/library/ms176056.aspx[^]

Posted 1-Feb-11 1:10am

Prerak Patel

Comments

Manas Bhardwaj 1-Feb-11 7:13am

+5.

Rayalacheruvu Hemanth 24-Jul-19 13:51pm

yeah, its working.
thanks lot.

Abhinav S · Accepted Answer · 2011-02-01T01:11:00

"When you concatenate null values, either the concat null yields null setting of sp_dboption or SET CONCAT_NULL_YIELDS_NULL determines the behavior when one expression is NULL. With either concat null yields null or SET CONCAT_NULL_YIELDS_NULL enabled ON, 'string' + NULL returns NULL. If either concat null yields null or SET CONCAT_NULL_YIELDS_NULL is disabled, the result is 'string'."

This was from http://msdn.microsoft.com/en-us/library/aa276862(v=sql.80).aspx[^].

Manas Bhardwaj · Accepted Answer · 2011-02-01T01:12:00

Solution 3

This is because CONCAT_NULL_YIELDS_NULL [^] is by default set as ON. YOu can turn it off in your query and the result will be affected.
Although, turning it off is not recommended and should be used carefully.

Posted 1-Feb-11 1:12am

Manas Bhardwaj