id  name city   salary  dept

SELECT salary WHERE salary > (SELECT AVG(salary) FROM *)

select * from b  where ref > (select avg(ref) from b);
select * from b  having ref > (select avg(ref) from b);

mysql> select * from b;
+------+------------+------+
| id   | d2         | ref  |
+------+------------+------+
|  300 | 2010-12-12 |    3 |
|  300 | 2011-12-12 |    2 |
|  300 | 2012-12-12 |    1 |
|  400 | 2011-12-12 |    1 |
+------+------------+------+
4 rows in set (0.00 sec)

mysql> select * from b  having ref > avg(ref);
+------+------------+------+
| id   | d2         | ref  |
+------+------------+------+
|  300 | 2010-12-12 |    3 |
+------+------------+------+
1 row in set (0.00 sec)

mysql> select * from b  having ref > (select avg(ref) from b);
+------+------------+------+
| id   | d2         | ref  |
+------+------------+------+
|  300 | 2010-12-12 |    3 |
|  300 | 2011-12-12 |    2 |
+------+------------+------+
2 rows in set (0.02 sec)

mysql> select * from b  where ref > (select avg(ref) from b);
+------+------------+------+
| id   | d2         | ref  |
+------+------------+------+
|  300 | 2010-12-12 |    3 |
|  300 | 2011-12-12 |    2 |
+------+------------+------+
2 rows in set (0.00 sec)

mysql> select *,avg(ref) from b  having ref > avg(ref);
+------+------------+------+----------+
| id   | d2         | ref  | avg(ref) |
+------+------------+------+----------+
|  300 | 2010-12-12 |    3 |   1.7500 |
+------+------------+------+----------+
1 row in set (0.00 sec)

SELECT Salary
FROM (
  SELECT
    Salary,
    AVG(Salary) OVER () AS AvgSalary
  FROM atable
) s
WHERE Salary > AvgSalary

SELECT *FROM table_name WHERE salary > avg(select salary from table_name)

select empno,e.deptno,sal
  from emp e, ( select deptno,avg(sal) avsal
                  from emp
              group by deptno
              ) a
 where e.sal > a.avsal
   and e.deptno = a.deptno;

select salary from Employee where salary > (select ava(salary) from employee)

select e1.* from emp e1  inner join (select avg(sal) avg_sal,dept_id from emp group by
dept_id) as e2 on e1.dept_id=e2.dept_id and e1.sal>e2.avg_sal

select * from emp where sal > (select avg(sal) from emp)