CASE Statements & Conditional Logic

Intermediate

15 minutes

20 minutes

15 minutes

SELECT & Data Retrieval

WHERE Clause & Filtering

Master CASE expressions for conditional logic in SQL

Understand simple CASE vs searched CASE syntax

Use CASE in SELECT, WHERE, ORDER BY, and aggregate functions

Handle NULL values with CASE and COALESCE

Optimize CASE performance with proper ordering

Apply CASE for data transformation and categorization

CASE statements enable conditional logic in SQL - categorize data, transform values, handle NULL, create calculated fields. Used in every report, dashboard, and data transformation pipeline. Essential for business logic in queries.

CASE is the SQL equivalent of IF-ELSE in programming. Critical for data analysts, BI developers, and backend engineers. Used in 80% of production queries for categorization, formatting, and conditional calculations.

CASE is SQL's conditional expression - like IF-ELSE in programming. It evaluates conditions and returns different values based on which condition is TRUE.

**Two CASE Syntaxes:**

**Simple CASE:**

Compares expression to values:

CASE column

WHEN value1 THEN result1

WHEN value2 THEN result2

ELSE default_result

END

**Searched CASE:**

Evaluates boolean conditions:

CASE

WHEN condition1 THEN result1

WHEN condition2 THEN result2

ELSE default_result

END

**Key Concepts:**

• Evaluates top-to-bottom, stops at first TRUE

• ELSE clause is optional (returns NULL if no match)

• Can be used in SELECT, WHERE, ORDER BY, GROUP BY

• Returns single value per row

• All THEN results must be same data type

SELECT

employee_id,

CASE department