SQL MCQs

Question 1

What does it mean for a SQL query to use a window function?

Accepted Answer

It performs a calculation across a set of rows related to the current row without collapsing them into a single result, unlike GROUP BY

Answer

It permanently changes the layout of the result window in a query tool

Answer

It only applies to date and time columns

Answer

It automatically limits the query to the first ten rows

Question 2

Which SQL clause is used to filter rows AFTER aggregating with GROUP BY?

Accepted Answer

HAVING

Answer

WHERE

Answer

ORDER BY

Answer

LIMIT

Question 3

Which JOIN returns all rows from the left table and matching rows from the right table, filling with NULL where there is no match?

Accepted Answer

LEFT JOIN

Answer

INNER JOIN

Answer

RIGHT JOIN

Answer

CROSS JOIN

Question 4

Which SQL clause is used to filter group results created by the GROUP BY clause?

Accepted Answer

HAVING

Answer

WHERE

Answer

ORDER BY

Answer

LIMIT

Question 5

Which join returns all rows from the left table, and matching rows from the right table, filling nulls if no match exists?

Accepted Answer

LEFT JOIN

Answer

INNER JOIN

Answer

FULL OUTER JOIN

Answer

CROSS JOIN

Question 6

Which SQL operator returns true if a subquery returns at least one row?

Accepted Answer

EXISTS

Answer

IN

Answer

ANY

Answer

HAVING

Question 7

Which SQL constraint uniquely identifies each record in a database table and disallows NULL values?

Accepted Answer

PRIMARY KEY

Answer

FOREIGN KEY

Answer

UNIQUE

Answer

CHECK

Question 8

What is the Cartesian product join of two tables with M and N rows respectively?

Accepted Answer

M * N rows via CROSS JOIN

Answer

M + N rows

Answer

Max(M, N) rows

Answer

Min(M, N) rows

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SQL MCQ Questions

What does it mean for a SQL query to use a window function?

Which SQL clause is used to filter rows AFTER aggregating with GROUP BY?

Which JOIN returns all rows from the left table and matching rows from the right table, filling with NULL where there is no match?

Which SQL clause is used to filter group results created by the GROUP BY clause?

Which join returns all rows from the left table, and matching rows from the right table, filling nulls if no match exists?

Which SQL operator returns true if a subquery returns at least one row?

Which SQL constraint uniquely identifies each record in a database table and disallows NULL values?

What is the Cartesian product join of two tables with M and N rows respectively?