IN SUB QUERY WHICH LINE IS HAVING ERROR

Question

HI,
OTN MEMBERS.
I HAVE ONE QUESTION THAT WHEN WRITING THE FOLLOWING QUERY.
1) SELECT ENAME,SAL
2) FROM EMP
3) WHERE EMPNO = (
4) SELECT EMPNO
5) FROM EMP
6) WHERE SAL >100 OR SAL <5000)
AS THIS QUERY WILL NOT RUN B'COZ SUBQUERY GENERATES MORE
THEN ONE RESULT AND THE MAIN QUERY IS HAVING (=) SINGLE
ROW OPERATOR , BUT LINE WIZE WHICH LINE SHOULD I CHOOSE AS
WRONG , B'COZ THERE IS TWO OPTIONS :-
3) WHERE EMPNO =
AND LINE
6) WHERE SAL>100 OR SAL<5000
THANKS

Answer 1

It depends on what you need.
6) WHERE SAL >100 OR SAL <5000) : this line generates more than one row, so if you need only one row you have to change it.
If you can accept more than one row, then line 3 should be :
3) WHERE EMPNO in (
BTW, WHERE SAL >100 OR SAL <5000 always extracts all rows. Shouldn't be WHERE SAL >100 and SAL <5000 ?