Order of SQL query execution

 In SQL, the order you write the clauses in a query is not the same as the order in which the database engine executes them.

Here’s the logical order of execution of SQL clauses:

Step	Clause	Description
1️⃣	FROM	Identifies source tables and joins data.
2️⃣	WHERE	Filters rows before grouping.
3️⃣	GROUP BY	Groups rows based on specified columns.
4️⃣	HAVING	Filters groups after aggregation.
5️⃣	SELECT	Selects columns or expressions to return.
6️⃣	DISTINCT	Removes duplicate rows from the result set.
7️⃣	ORDER BY	Sorts the result set.
8️⃣	LIMIT / OFFSET	Returns a subset of the result (pagination).

EXAMPLE:

SELECT department, COUNT(*) AS employee_count

FROM employees

WHERE status = 'active'

GROUP BY department

HAVING COUNT(*) > 10

ORDER BY employee_count DESC

LIMIT 5;

Execution order:

1. FROM employees

2. WHERE status = 'active'

3. GROUP BY department

4. HAVING COUNT(*) > 10

5. SELECT department, COUNT(*) AS employee_count

6. ORDER BY employee_count DESC

7. LIMIT 5