Take Quiz - 🗂️ SQL & Databases

1. Which SQL function is used to get the rank of a row in a result set with gaps in ranking?

DENSE_RANK() RANK() ROW_NUMBER() NTILE()

2. What does the EXISTS keyword do in a SQL query?

Returns number of rows Checks if a subquery returns any rows Creates a table Checks column type

3. In SQL, which of the following statements about INDEX is TRUE?

Index slows down SELECT queries Index increases storage but speeds up search Index reduces data accuracy Index works only with UNIQUE keys

4. What is the purpose of the WITH clause (CTE - Common Table Expression)?

To declare variables To improve readability and reuse subqueries To insert rows To update multiple tables

5. What happens if you omit the WHERE clause in an UPDATE statement?

Only one row is updated No row is updated All rows are updated Syntax error

6. Which type of JOIN returns all unmatched rows from both tables?

INNER JOIN LEFT JOIN RIGHT JOIN FULL OUTER JOIN

7. What is the purpose of VIEW in SQL?

Physically stores data Stores procedures A virtual table based on a SELECT query Deletes table

8. Which SQL isolation level provides the highest level of data integrity?

READ UNCOMMITTED READ COMMITTED REPEATABLE READ SERIALIZABLE

9. Which normal form removes partial dependency?

1NF 2NF 3NF 4NF

10. What is the output of this query? SELECT department, COUNT(*) OVER (PARTITION BY department) FROM employees;

Total count of employees Count of employees in each department Error Average salary