Pull Columns based on row value

Question

I have a table X

ID      A       B       C        D
1       T       T       F        T
2       F       T       F        T
3       T       F       T        F

So if my input is 1 for ID, then I want all column names that have value T for row 1. In above case A,B,D or If ID is 3 then A and C.

How could I list these columns?

Answer 1

You can use UNPIVOT for this

SELECT Y
FROM Table1
UNPIVOT (X FOR Y IN ([A], [B], [C], [D])) U
WHERE [ID] = 1 AND X = 'T'

Returns

+---+
| Y |
+---+
| A |
| B |
| D |
+---+

SQL Fiddle