SQL CASE

CASE lets you add if-else logic inside SQL statements. It’s great for transforming data or creating new categorized columns.

🔹 Basic Syntax (Simple CASE)

SELECT
  column,
  CASE column
    WHEN value1 THEN result1
    WHEN value2 THEN result2
    ELSE result_default
  END AS alias_name
FROM table_name;

🔹 Example: Classify Employees by Salary

SELECT
  employee_name,
  salary,
  CASE
    WHEN salary >= 100000 THEN 'High'
    WHEN salary >= 50000 THEN 'Medium'
    ELSE 'Low'
  END AS salary_level
FROM employees;

🔹 Searched CASE Syntax (More flexible)

SELECT
  column,
  CASE
    WHEN condition1 THEN result1
    WHEN condition2 THEN result2
    ELSE result_default
  END AS alias_name
FROM table_name;

🧠 Quick Recap

Concept	Explanation
`CASE`	Adds conditional logic inside queries
Simple CASE	Compares a column to fixed values
Searched CASE	Uses conditions with WHEN
Returns	Values or expressions based on conditions

✅ Use CASE to create dynamic, condition-based outputs inside your queries