SQL Execution and Query Shape | Dataford Interview Questions

How does a SQL query usually look like, and how is it executed?

Write a PostgreSQL query that summarizes active employees by operational department, then explain how PostgreSQL processes the query logically and executes it physically.

Output

One row per qualifying department.
Columns: department_name, active_employee_count, and avg_active_salary.
Include operational departments with at least two active employees and an average active salary of at least 70000.
Order by average salary descending, then department name ascending.

Schema

departments

Column	Type	Description
department_idPK	INT	Unique department identifier
department_name	VARCHAR(100)	Department name
is_operational	BOOLEAN	Whether the department is operational

employees

Column	Type	Description
employee_idPK	INT	Unique employee identifier
employee_name	VARCHAR(100)	Employee name
department_id	INT	Employee department identifier
status	VARCHAR(20)	Employment status
salary	NUMERIC(12,2)	Annual salary

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Problem