SQL Date-Based Employee Lookup | Dataford Interview Questions

Abzooba maintains employee salary history with an effective date for each salary change. Write a PostgreSQL query that reports each employee's latest salary effective on a fixed reporting date, DATE '2026-08-30', and the salary immediately before it.

Output

Return one row per employee, including employees without an eligible salary record.
Include employee_id, employee_name, current_salary, previous_salary, and current_effective_from.
Consider only salary records where effective_from <= DATE '2026-08-30'. Rows with no eligible salary record must have NULL salary fields.
Order the results by employee_id ascending.

Schema

employees

Column	Type	Description
employee_idPK	INTEGER	Unique employee identifier
employee_name	VARCHAR(100)	Employee's full name
department	VARCHAR(80)	Abzooba department

salary_history

Column	Type	Description
salary_history_idPK	INTEGER	Unique salary history identifier
employee_id	INTEGER	References employees.employee_id
salary	NUMERIC(12,2)	Salary amount
effective_from	DATE	Date the salary became effective
effective_to	DATE	Date the salary ended, if known

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