case-when

CASE — SQL ichidagi if/elif/else. Yangi hisoblangan ustun yasash uchun.

SELECT name,
       CASE
           WHEN grade >= 90 THEN 'A'
           WHEN grade >= 75 THEN 'B'
           WHEN grade >= 60 THEN 'C'
           ELSE 'F'
       END AS letter
FROM students;

Shartli sanash

SELECT faculty,
       SUM(CASE WHEN grade >= 4 THEN 1 ELSE 0 END) AS good,
       COUNT(*) AS total
FROM students GROUP BY faculty;

Shartlar yuqoridan pastga tekshiriladi — birinchi mos kelgani olinadi.