Substitute one columns results for another

How do you write the SQL statment so that it will return results from two columns and in the case where one of the two columns has a null record, substitute the column with the result from the other column.

Simalar to COALESCE but with two columns

SELECT COLUMN1, COLUMN2
FROM TABEL1
WHERE IDCOLUMN = 'USERID'

Code (markup):

I know this is not right but its the same Idea...

SELECT COALESCE(COLUMN1, COLUMN2) AS NEWCOLUMN
FROM TABEL1
WHERE IDCOLUMN = 'USERID'

Code (markup):

 

SELECT c1, IF (c2 IS NULL, c1, c2)
FROM table1
...