COUNT

Source data — Pattern 4: Aggregation

All queries run against the shared employees table (see schema.sql) — no new columns needed for this pattern.

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What it does

COUNT(*) counts rows, including ones with NULLs in every column. COUNT(column_name) counts only the rows where that specific column isn't NULL — the two can give different answers on the same table, so pick deliberately.

Problem

Count total employees.

SELECT COUNT(*) AS total_employees
FROM employees;

Result