SQL MCQ questions with answers

Practice SQL MCQ questions with answers on joins, subqueries, normalization, aggregation, and transactions.

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SQL MCQ questions with answers

SQL is primarily used to:

A primary key should:

Which statement best describes a foreign key?

Which option correctly compares `WHERE` and `HAVING`?

Which statement about `DELETE`, `TRUNCATE`, and `DROP` is correct?

In SQL, `NULL` means:

Which condition is correct for checking missing values in SQL?

`GROUP BY` is mainly used to:

An `INNER JOIN` returns:

A `LEFT JOIN` returns:

A self join is used when:

`UNION` differs from `UNION ALL` because `UNION`:

A subquery is:

Which statement best compares `IN` and `EXISTS`?

A CTE is introduced using:

To list all customers even if they have no matching orders, which join is most appropriate?

Which of the following is an aggregate function?

If a column contains nulls, `COUNT(column)` will:

`COUNT(*)` returns:

A window function differs from `GROUP BY` mainly because it:

Which function gives every row a unique running number even when values tie?

Which function leaves gaps in ranking after tied values?

Which tool is commonly used to assign labels like 'High', 'Medium', and 'Low' in query output?

If you only want unique rows in the query result, which keyword is most direct?

Normalization is mainly used to:

1NF mainly requires that:

Denormalization is usually considered when:

A composite key uses:

Which of the following is a constraint?

Which statement best describes a view?

An index is mainly created to:

Which statement about indexes is correct?

A transaction is best described as:

In ACID, atomicity means:

Which ACID property is most directly about committed data surviving a crash?

Which command makes current transaction changes permanent?

Which command is used to undo uncommitted transaction work?

A `SAVEPOINT` is useful because it:

Isolation levels mainly control:

A strong first step for tuning a slow SQL query is to:

SQL MCQ questions with answers

SQL is primarily used to:

A primary key should:

Which statement best describes a foreign key?

Which option correctly compares `WHERE` and `HAVING`?

Which statement about `DELETE`, `TRUNCATE`, and `DROP` is correct?

In SQL, `NULL` means:

Which condition is correct for checking missing values in SQL?

`GROUP BY` is mainly used to:

An `INNER JOIN` returns:

A `LEFT JOIN` returns:

A self join is used when:

`UNION` differs from `UNION ALL` because `UNION`:

A subquery is:

Which statement best compares `IN` and `EXISTS`?

A CTE is introduced using:

To list all customers even if they have no matching orders, which join is most appropriate?

Which of the following is an aggregate function?

If a column contains nulls, `COUNT(column)` will:

`COUNT(*)` returns:

A window function differs from `GROUP BY` mainly because it:

Which function gives every row a unique running number even when values tie?

Which function leaves gaps in ranking after tied values?

Which tool is commonly used to assign labels like 'High', 'Medium', and 'Low' in query output?

If you only want unique rows in the query result, which keyword is most direct?

Normalization is mainly used to:

1NF mainly requires that:

Denormalization is usually considered when:

A composite key uses:

Which of the following is a constraint?

Which statement best describes a view?

An index is mainly created to:

Which statement about indexes is correct?

A transaction is best described as:

In ACID, atomicity means:

Which ACID property is most directly about committed data surviving a crash?

Which command makes current transaction changes permanent?

Which command is used to undo uncommitted transaction work?

A `SAVEPOINT` is useful because it: