This guide is specifically for MySQL syntax.

SQL CASE WHEN Statement Examples

Add conditional logic to queries using CASE WHEN THEN ELSE END.

Quick Answer

SELECT name, CASE WHEN salary > 50000 THEN 'High' ELSE 'Low' END as level FROM employees;

Explanation

CASE evaluates conditions in order and returns the result when a condition is true. ELSE handles unmatched cases. Always end with END.

Query Variants

Simple

SELECT name,
  CASE
    WHEN salary > 100000 THEN 'Executive'
    WHEN salary > 50000 THEN 'Senior'
    ELSE 'Junior'
  END as level
FROM employees;

In Aggregate

SELECT department,
  SUM(CASE WHEN gender = 'M' THEN 1 ELSE 0 END) as male_count,
  SUM(CASE WHEN gender = 'F' THEN 1 ELSE 0 END) as female_count
FROM employees
GROUP BY department;

In Orderby

SELECT * FROM tasks
ORDER BY CASE priority
  WHEN 'high' THEN 1
  WHEN 'medium' THEN 2
  ELSE 3
END;

Pro Tips

• Conditions are evaluated in order
• ELSE is optional but recommended
• Can be used in SELECT, WHERE, ORDER BY

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MySQL-Specific Notes

This page covers MySQL syntax. Other databases may have different syntax for similar operations.