Why to use COALESCE instead of ISNULL

re: Why to use COALESCE instead of ISNULL

Aaron Bertrand — Thu, 07 Feb 2013 01:44:01 GMT

I talk about this issue and a bunch of others in the following tip:

http://www.mssqltips.com/sqlservertip/2689/deciding-between-coalesce-and-isnull-in-sql-server/

The only place where ISNULL trumps COALESCE is when the expression is a subquery - with COALESCE it may be evaluated twice.

re: Why to use COALESCE instead of ISNULL

Francesco Quaratino — Thu, 07 Feb 2013 10:34:27 GMT

really scary!

re: Why to use COALESCE instead of ISNULL

Paul White — Thu, 07 Feb 2013 19:13:20 GMT

I prefer ISNULL in most cases for a range of detailed reasons, many related to better optimizer reasoning with ISNULL. The argument presented here is one small aspect of the differences which I do not find at all compelling.

re: Why to use COALESCE instead of ISNULL

gbn — Fri, 08 Feb 2013 10:58:10 GMT

I prefer ISNULL too to avoid accidental datatype conversions due to datatype precedence. And as Paul said.

Discussion here: http://dba.stackexchange.com/q/4274/630