COALESCE() for blank (but not null) fields

Question

I have two fields that I'm comparing with MySQL's function COALESCE(). For example, COALESCE(Field1, Field2). The problem is, Field1 is sometimes blank but not null; since it's not null COALESCE() selects Field1, even though its blank. In that case, I need it to select Field2.

I know I can write a if-then-else (CASE) statement in the query to check for this, but is there a nice simple function like COALESCE() for blank-but-not-null fields?

Solution 1

SELECT IFNULL(NULLIF(Field1,''),Field2)

NULLIF returns a NULL if Field1 is blank, while IFNULL returns Field1 if it's not blank or NULL and Field2 otherwise.

Solution 2

I know I'm late to the party here, but there is a way to do this while still using COALESCE(). This would then work if your value was NULL or ''.

Select COALESCE(NULLIF(Field1,''), Field2)

Solution 3

You can use a CASE expression:

CASE WHEN Field1 <> '' THEN Field1 ELSE Field2 END

Comments

[Luke Shaheen]

That's what I meant by if-then-else; I was looking for a cleaner, one-line solution

[Luke Shaheen]

I could do the same, but with COALESCE correct? COALESCE(NULLIF(Field1,''),Field2) - is there a speed/processing load difference?

[Luke Shaheen]

Interesting response about COALESCE vs IFNULL here: stackoverflow.com/questions/4747877/…

[Luke Shaheen]

See the comment on the selected answer :)

[Beachhouse]

Well there you go! Didn't see that.