Paytm SQL Interview Question

Описание: In this video, I walk through a real SQL interview question asked for a Senior Analytics Engineer position. At this level, interviewers care far more about your approach, reasoning, and clarity of thought than just the final SQL query.

CREATE TABLE employee_timetable (
emp_id INT NOT NULL,
emp_name VARCHAR(100) NOT NULL,
dep_id INT NOT NULL,
in_out VARCHAR(3) NOT NULL
CHECK (in_out IN ('in', 'out')),
in_out_time TIMESTAMP NOT NULL
);

INSERT INTO employee_timetable (emp_id, emp_name, dep_id, in_out, in_out_time) VALUES

-- Employee 101
(101, 'Alice', 10, 'in', '2026-01-28 09:00:00'),
(101, 'Alice', 10, 'out', '2026-01-28 13:00:00'),
(101, 'Alice', 10, 'in', '2026-01-28 14:10:00'),
(101, 'Alice', 10, 'out', '2026-01-28 18:00:00'),

-- Employee 102
(102, 'Bob', 20, 'in', '2026-01-28 08:45:00'),
(102, 'Bob', 20, 'out', '2026-01-28 12:30:00'),
(102, 'Bob', 20, 'in', '2026-01-28 13:15:00'),
(102, 'Bob', 20, 'out', '2026-01-28 17:45:00'),

-- Employee 103
(103, 'Charlie', 10, 'in', '2026-01-28 09:10:00'),
(103, 'Charlie', 10, 'out', '2026-01-28 12:50:00'),
(103, 'Charlie', 10, 'in', '2026-01-28 13:40:00'),
(103, 'Charlie', 10, 'out', '2026-01-28 18:20:00'),

-- Employee 104
(104, 'Diana', 30, 'in', '2026-01-28 10:00:00'),
(104, 'Diana', 30, 'out', '2026-01-28 14:05:00'),
(104, 'Diana', 30, 'in', '2026-01-28 15:00:00'),
(104, 'Diana', 30, 'out', '2026-01-28 19:00:00'),

-- Employee 105
(105, 'Ethan', 20, 'in', '2026-01-28 10:05:00'),
(105, 'Ethan', 20, 'out', '2026-01-28 13:00:00'),
(105, 'Ethan', 20, 'in', '2026-01-28 14:00:00'),
(105, 'Ethan', 20, 'out', '2026-01-28 17:30:00'),

-- Employee 106
(106, 'Fiona', 30, 'in', '2026-01-28 10:15:00'),
(106, 'Fiona', 30, 'out', '2026-01-28 12:45:00'),
(106, 'Fiona', 30, 'in', '2026-01-28 13:30:00'),
(106, 'Fiona', 30, 'out', '2026-01-28 18:00:00'),

-- Employee 107
(107, 'George', 10, 'in', '2026-01-28 10:30:00'),
(107, 'George', 10, 'out', '2026-01-28 13:20:00'),
(107, 'George', 10, 'in', '2026-01-28 14:10:00'),
(107, 'George', 10, 'out', '2026-01-28 17:50:00'),

-- Employee 108
(108, 'Hannah', 40, 'in', '2026-01-28 10:00:00'),
(108, 'Hannah', 40, 'out', '2026-01-28 12:30:00'),
(108, 'Hannah', 40, 'in', '2026-01-28 13:15:00'),
(108, 'Hannah', 40, 'out', '2026-01-28 16:45:00'),

-- Employee 109
(109, 'Ian', 20, 'in', '2026-01-28 10:20:00'),
(109, 'Ian', 20, 'out', '2026-01-28 13:40:00'),
(109, 'Ian', 20, 'in', '2026-01-28 14:30:00'),
(109, 'Ian', 20, 'out', '2026-01-28 18:00:00');

To demonstrate this clearly, I solve the same problem using two different SQL approaches:
A simple, logic-driven solution that relies on strong SQL fundamentals
An alternative solution using window functions, showcasing a more advanced and scalable approach

By comparing both methods, you will understand why different SQL strategies exist, when to use each, and how to justify your approach during senior-level interviews.

What You Will Learn in This Video:
Writing clean, maintainable SQL
When a simple approach is better than an advanced one
Practical use of window functions in real interview scenarios
How to explain your logic clearly to interviewers

This type of question is commonly used to test depth of understanding, optimization thinking, and SQL maturity, especially for analytics engineering and senior data roles.

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