use of Isnull() in optimization

Question

Is any diff in below query in term of performance??

select COLUMN1,column2 from table
where COLUMN1 is not null
and COLUMN1 <>'';

select COLUMN1,column2 from table
where isnull(Column1,'')<>'';

http://stackoverflow.com/questions/8924913/is-there-is-any-performance-issue-while-using-isnull-in-sql-server — Sebastian Brosch, May 12 '17 at 06:56

score 0 · Accepted Answer · answered May 12 '17 at 07:05

You can obtain an execution plan for your query to determine the cost of that operation.

How to do it and the output format really depends on each database product.

In the case of SQL server it may look like:

My intuition tells me that operation in particular should not be expensive. What would rather be expensive is to query a column that is not indexed.

1 Answers1