SQL Server Case expression conditions

Question

I am currently working on a data flow and have been given a specific requirement that i am trying to complete.

In my table I have a column which is partially NULL due to a couple of reasons.

What I'm trying to do is write a case expression within my select statement that has two conditions:

When NULL use a different value from another column (which is pulled from another table using a join)

If the column is still NULL (in both cases) then use a different value from another column in the table which will ensure the column is populated.

So basically, if it's NULL do this, if its still NULL, then do this which will mean my column is populated as i intend.

I've been playing around but have been unable to produce the required result. Is this something that can be achieved using a CASE expression ?

Any help/advice would be appreciated.

Thanks.

Answer 1

You are describing the coalesce() function:

coalesce(col1, col2, col3)

You can use this in either a select or update.