I found this snippet of SQL in a view and I am rather puzzled by it's purpose (actual SQL shortened for brevity):
SELECT
COALESCE(b.Foo, NULL) AS Foo
FROM a
LEFT JOIN b ON b.aId=a.Id
I cannot think of a single reason of the purpose of coalescing with null instead of just doing this:
SELECT
b.Foo AS Foo
FROM a
LEFT JOIN b ON b.aId=a.Id
Or at the very least don't include the NULL explicitly:
SELECT
COALESCE(b.Foo) AS Foo
FROM a
LEFT JOIN b ON b.aId=a.Id
I don't know who authored this (so I cannot ask), when it was authored, or for what specific MS SQL Server version it was written for (pre-2008 for sure though).
Is there any valid reason to coalesce with NULL instead of just selecting the column directly? I can't help but laugh and write it off as a rookie mistake but it makes me wonder if there is some "fringe case" that I don't know about.