Conditional Aggregation

How can we count employees by condition?

Advanced⏱ 3 Minutes⭐ 1250 XP

🤔 THE QUESTION

How can we count employees by condition?

💡 WHAT IS IT?

Nesting CASE inside COUNT() computes conditional counts in a single table scan without subqueries.

🎯 WHAT IS IT USED FOR?

Pivot-style metric reporting, active vs inactive counts, department breakdown columns.

💻 EXAMPLE

SELECT
COUNT(CASE WHEN department = 'Engineering' THEN 1 END) AS engineers,
COUNT(CASE WHEN department = 'Analytics' THEN 1 END) AS analysts
FROM employees;

🎯 Mission Objectives

Practice typing production-grade SQL code for Conditional Aggregation.

✓ COUNT(CASE ...)
✓ Conditional aggregation
✓ Single-pass pivoting
✓ Categorical counters

🚀 Start Mission

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