ORA-01791: not a SELECTed expression

ORA-01791:	not a SELECTed expression
Cause:	There is an incorrect ORDER BY item. The query is a SELECT DISTINCT query with an ORDER BY clause. In this context, all ORDER BY items must be constants, SELECT list expressions, or expressions whose operands are constants or SELECT list expressions.
Action:	Remove the inappropriate ORDER BY item from the SELECT list and retry the statement. Once we remove the ORDER By clause the sql should work without any error.