Why combining result sets is useful in MySQL - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to combine two tables using UNION.

MySQL

SELECT name FROM employees [1] SELECT name FROM managers;

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

AWHERE

BUNION

CINTERSECT

DJOIN

Attempts:

3 left

💡 Hint

Common Mistakes

Using JOIN instead of UNION causes syntax errors.

Using WHERE does not combine result sets.

The UNION keyword combines the results of two SELECT statements into one result set.

2fill in blank

medium

Complete the code to combine two queries and remove duplicate rows.

MySQL

SELECT city FROM customers [1] SELECT city FROM suppliers;

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

AUNION ALL

BJOIN

CUNION

DEXCEPT

Attempts:

3 left

💡 Hint

Common Mistakes

Using UNION ALL keeps duplicates, which is not desired here.

JOIN does not combine result sets vertically.

UNION removes duplicate rows by default when combining result sets.

3fill in blank

hard

Fix the error in combining two SELECT statements to include all rows, even duplicates.

MySQL

SELECT product FROM inventory [1] SELECT product FROM warehouse;

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

AUNION ALL

BJOIN

CINTERSECT

DUNION

Attempts:

3 left

💡 Hint

Common Mistakes

Using UNION removes duplicates unintentionally.

JOIN does not combine result sets vertically.

UNION ALL combines result sets including duplicates, unlike UNION which removes them.

4fill in blank

hard

Fill both blanks to combine two queries and sort the combined results by city.

MySQL

SELECT city FROM customers [1] SELECT city FROM suppliers [2] city ASC;

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

AUNION

BORDER BY

CUNION ALL

DGROUP BY

Attempts:

3 left

💡 Hint

Common Mistakes

Using GROUP BY instead of ORDER BY does not sort the results.

Using UNION ALL instead of UNION changes duplicate handling.

Use UNION to combine and ORDER BY to sort the results.

5fill in blank

hard

Fill all three blanks to combine two SELECT queries, include duplicates, and sort by name descending.

MySQL

SELECT name FROM employees [1] SELECT name FROM contractors [2] name [3];

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

AUNION ALL

BORDER BY

CDESC

DGROUP BY

Attempts:

3 left

💡 Hint

Common Mistakes

Using GROUP BY instead of ORDER BY for sorting.

Using UNION instead of UNION ALL removes duplicates.

UNION ALL includes duplicates, ORDER BY sorts, and DESC sorts descending.