How to Use CASE Statements in MySQL

Last updated July 25, 2026 · By the SaturnSQL team

Use CASE WHEN condition THEN value ... ELSE value END inside SELECT to derive columns, and inside ORDER BY for custom sort orders. The compact CASE expr WHEN value form compares one expression against literals.

SELECT id,
       amount,
       CASE
         WHEN amount >= 100 THEN 'large'
         WHEN amount >= 20 THEN 'medium'
         ELSE 'small'
       END AS size
FROM orders;

Custom sort order

SELECT * FROM orders
ORDER BY CASE status
  WHEN 'pending' THEN 1
  WHEN 'shipped' THEN 2
  WHEN 'delivered' THEN 3
  ELSE 4
END, created_at DESC;

Without an ELSE, non-matching rows get NULL. CASE is an expression, so it also works in WHERE, GROUP BY, and aggregate arguments like SUM(CASE WHEN ... THEN 1 ELSE 0 END).

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How to Use CASE Statements in MySQL

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