Why set operations are needed in SQL - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to combine two tables and get all unique rows.

SQL

SELECT * FROM table1 [1] SELECT * FROM table2;

Drag options to blanks, or click blank then click option'

AUNION

BJOIN

CINTERSECT

DWHERE

Attempts:

3 left

💡 Hint

Common Mistakes

Using JOIN instead of UNION causes a different result.

Using WHERE is incorrect for combining tables.

The UNION operation combines rows from two tables and removes duplicates, giving all unique rows.

2fill in blank

medium

Complete the code to find rows common to both tables.

SQL

SELECT * FROM table1 [1] SELECT * FROM table2;

Drag options to blanks, or click blank then click option'

AINTERSECT

BJOIN

CEXCEPT

DUNION

Attempts:

3 left

💡 Hint

Common Mistakes

Using UNION returns all rows, not just common ones.

Using EXCEPT returns rows only in the first table.

The INTERSECT operation returns only rows that appear in both tables.

3fill in blank

hard

Fix the error in the code to get rows in table1 but not in table2.

SQL

SELECT * FROM table1 [1] SELECT * FROM table2;

Drag options to blanks, or click blank then click option'

AUNION

BINTERSECT

CJOIN

DEXCEPT

Attempts:

3 left

💡 Hint

Common Mistakes

Using INTERSECT returns common rows, not unique ones.

Using UNION combines all rows, including duplicates.

The EXCEPT operation returns rows from the first table that are not in the second table.

4fill in blank

hard

Fill both blanks to combine two tables and keep all rows including duplicates.

SQL

SELECT * FROM table1 [1] SELECT * FROM table2 [2] id;

Drag options to blanks, or click blank then click option'

AUNION ALL

BUNION

CORDER BY

DWHERE

Attempts:

3 left

💡 Hint

Common Mistakes

Using UNION removes duplicates.

Using WHERE is not valid here.

UNION ALL combines all rows from both tables including duplicates. ORDER BY sorts the final result.

5fill in blank

hard

Fill all three blanks to find rows in table1 not in table2 and sort by id.

SQL

SELECT * FROM table1 [1] SELECT * FROM table2 [2] id [3];

Drag options to blanks, or click blank then click option'

AEXCEPT

BORDER BY

CASC

DDESC

Attempts:

3 left

💡 Hint

Common Mistakes

Using DESC sorts in descending order, not ascending.

Using UNION returns all rows, not just unique ones.

EXCEPT finds rows in table1 not in table2. ORDER BY sorts the result by id in ascending order (ASC).