MySQL : Selecting alternative field if given field is empty

Question

Hi, I wonder if is it possible to run mysql command which can select an alternative field if the first given field is empty, on the same table.

Example : I have table called "posts" which have "intro" and "content". In the same statement I would like to select as a result "content" if "intro" is empty, but not having both in the result array.

Thanks in advance

Answer 1

You can use IF function:

SELECT IF(LENGTH(intro)>0, intro, content) 
FROM posts

Or you can test for NULL if you mean that empty is NULL

Answer 2

Coalesce is what you are looking for.

SELECT COALESCE(intro, content) AS column1
FROM table

Assuming intro is null and not a zero length string.

Answer 3

There two potential ways. When way is with a case statement.

Select case when field1 <> '' then field2 else field1 end

or you you can use coalesce.

select coalesce(field1, field2)