Data and Analytics SQL and Database Fundamentals

Question 1

Which SQL clause is used to filter rows after aggregation?

Accepted Answer

HAVING

Answer

WHERE

Answer

GROUP BY

Answer

ORDER BY

Question 2

What does a PRIMARY KEY constraint enforce in a relational database?

Accepted Answer

Unique, non-null values per row

Answer

Referential integrity

Answer

Default column values

Answer

Column data types

Question 3

Which SQL JOIN returns only rows where there is a match in both tables?

Accepted Answer

INNER JOIN

Answer

LEFT JOIN

Answer

RIGHT JOIN

Answer

FULL OUTER JOIN

Question 4

What is the purpose of an index in a relational database?

Accepted Answer

To speed up data retrieval queries

Answer

To enforce referential integrity

Answer

To normalize table structure

Answer

To encrypt stored data

Question 5

Which normal form eliminates transitive dependencies?

Accepted Answer

3NF

Answer

1NF

Answer

2NF

Answer

BCNF

Question 6

What does the SQL DISTINCT keyword do?

Accepted Answer

Removes duplicate rows from the result set

Answer

Sorts results alphabetically

Answer

Filters NULL values

Answer

Limits the number of rows returned