IF

1
SELECT name, age,
2
  IF(age >= 18, 'Adult', 'Minor') AS category
3
FROM users;

1
SELECT product,
2
  IF(is_active, 'Yes', 'No') AS active_status
3
FROM products;

1
SELECT score,
2
  IF(score >= 90, 'A',
3
    IF(score >= 80, 'B',
4
      IF(score >= 70, 'C', 'F')
5
    )
6
  ) AS grade
7
FROM students;