This guide is specifically for MySQL syntax.

How to SQL CASE WHEN Statement Examples in SQL

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.