Subquery & CTE

Pecah masalah kompleks jadi langkah yang terbaca.

  WITH rekap AS (
    SELECT course_id, COUNT(*) AS jml
    FROM lessons GROUP BY course_id
  )
  SELECT c.title, r.jml
  FROM courses c JOIN rekap r ON r.course_id = c.id
  WHERE r.jml > 3;

CTE (`WITH`) lebih mudah dibaca daripada subquery bersarang.