Sup Dawg, I Heard You Like NULLS…

Quick note on NULLS: NULL means “Unknown Value”, not “0”. So adding a value to NULL results in NULL:

1 + NULL = NULL

Because NULL means “I Don’t Know”, adding two NULLS together does not equate to the same value; it’s still two indeterminate values.

NULL + NULL != NULL

You can work around this in T-SQL by using COALESCE.


declare @i VARCHAR(8) = NULL
declare @j VARCHAR(8) = NULL
SELECT @i

SELECT @i + 'bob'

SELECT COALESCE (@i, 'bob')

if @i = @j
select 'yes'
else
select 'no'

Author: Richie Lee

Full time computer guy, part time runner. Full time Dad, part time blogger. Pokémon Nut. Writer of fractured sentences. Maker of the best damn macaroni cheese you've ever tasted.

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