UNION ALL with duplicates in SQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to combine two tables including duplicates using UNION ALL.

SQL

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

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AINTERSECT

BUNION ALL

CUNION

DEXCEPT

Attempts:

3 left

💡 Hint

Common Mistakes

Using UNION instead of UNION ALL, which removes duplicates.

Using INTERSECT or EXCEPT which do not combine all rows.

The UNION ALL operator combines results from both queries and includes duplicates.

2fill in blank

medium

Complete the code to select all product IDs from two tables including duplicates.

SQL

SELECT product_id FROM sales_2023 [1] SELECT product_id FROM sales_2024;

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AUNION ALL

BUNION

CINTERSECT

DJOIN

Attempts:

3 left

💡 Hint

Common Mistakes

Using UNION which removes duplicates.

Using JOIN which is for combining columns, not rows.

UNION ALL returns all rows from both queries including duplicates.

3fill in blank

hard

Fix the error in the query to include duplicates from both tables.

SQL

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

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AUNION ALL

BUNION

CEXCEPT

DINTERSECT

Attempts:

3 left

💡 Hint

Common Mistakes

Using UNION which removes duplicates.

Using EXCEPT or INTERSECT which filter rows.

To include duplicates from both tables, use UNION ALL.

4fill in blank

hard

Fill both blanks to combine two queries including duplicates and order the results by name.

SQL

SELECT name FROM staff [1] SELECT name FROM interns ORDER BY name [2];

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AUNION ALL

BWHERE

CASC

DGROUP BY

Attempts:

3 left

💡 Hint

Common Mistakes

Using UNION instead of UNION ALL.

Using WHERE instead of ORDER BY direction.

UNION ALL combines all rows including duplicates, and ASC orders the results ascending by name.

5fill in blank

hard

Fill all three blanks to select all emails from two tables including duplicates, filter only active users, and order by email descending.

SQL

SELECT email FROM users_2022 WHERE status = [1] [2] SELECT email FROM users_2023 WHERE status = [3] ORDER BY email DESC;

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

A'active'

BUNION ALL

DUNION

Attempts:

3 left

💡 Hint

Common Mistakes

Using UNION which removes duplicates.

Using wrong status filter values.

Use 'active' to filter active users, and UNION ALL to combine all rows including duplicates.