SQL Aggregation

SQL Aggregation hanya boleh digunakan di SELECT, HAVING.
SQL Aggregation tidak boleh digunakan di klausa where.
Kalau akan menggunakan SQL Aggregation di klausa where, harus dibuat subquery-nya.

Contoh SUB Query :

SELECT nama
FROM mahasiswa
WHERE nim NOT
IN (
  SELECT idmhs
  FROM ambilmk
  WHERE idmk =1903
)
SELECT nama, nim, SUM( nilai * sks ) / SUM( sks ) AS ipk
FROM ambilmk, mk, mahasiswa
WHERE idmhs = nim
AND idmk = kodemk
GROUP BY idmhs
HAVING ipk < 3.5
LIMIT 0 , 30