question4.md

Lesson 04 — Filtering and Sorting Query Results

Source: SQLBolt — Lesson 4

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Concept

Removing Duplicates with DISTINCT

Query results can contain duplicate values across rows. Use DISTINCT to discard rows with duplicate column values.

SELECT DISTINCT column, another_column, …
FROM mytable
WHERE condition(s);

Ordering Results with ORDER BY

Data in a database is rarely stored in a useful order. Use ORDER BY to sort results alphanumerically by a column, ascending or descending.

SELECT column, another_column, …
FROM mytable
WHERE condition(s)
ORDER BY column ASC/DESC;

Limiting Results with LIMIT and OFFSET

Use LIMIT to cap the number of rows returned, and OFFSET to skip a number of rows before starting to count.

SELECT column, another_column, …
FROM mytable
WHERE condition(s)
ORDER BY column ASC/DESC
LIMIT num_limit OFFSET num_offset;

Note: LIMIT and OFFSET are applied last, after all other clauses. This is covered in detail in Lesson 12.

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Reference Table: movies

This lesson uses a scrambled version of the movies table to mimic real-world data. Note that the column is named director here.

id	title	director	year	length_minutes
1	A Bug's Life	John Lasseter	1998	95
2	Ratatouille	Brad Bird	2007	115
3	Brave	Brenda Chapman	2012	102
4	Cars	John Lasseter	2006	117
5	Monsters, Inc.	Pete Docter	2001	92
6	Toy Story 2	John Lasseter	1999	93
7	Finding Nemo	Andrew Stanton	2003	107
8	Toy Story	John Lasseter	1995	81
9	WALL-E	Andrew Stanton	2008	104
10	Up	Pete Docter	2009	101
11	The Incredibles	Brad Bird	2004	116
12	Cars 2	John Lasseter	2011	120
13	Toy Story 3	Lee Unkrich	2010	103
14	Monsters University	Dan Scanlon	2013	110

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Tasks & Solutions

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Task 1 — List all directors of Pixar movies (alphabetically), without duplicates

SELECT DISTINCT director FROM movies
ORDER BY director ASC;

Output:

director
Andrew Stanton
Brad Bird
Brenda Chapman
Dan Scanlon
John Lasseter
Lee Unkrich
Pete Docter

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Task 2 — List the last four Pixar movies released (ordered from most recent to least)

SELECT title, year FROM movies
ORDER BY year DESC
LIMIT 4;

Output:

title	year
Monsters University	2013
Brave	2012
Cars 2	2011
Toy Story 3	2010

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Task 3 — List the first five Pixar movies sorted alphabetically

SELECT title FROM movies
ORDER BY title ASC
LIMIT 5;

Output:

title
A Bug's Life
Brave
Cars
Cars 2
Finding Nemo

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Task 4 — List the next five Pixar movies sorted alphabetically

SELECT title FROM movies
ORDER BY title ASC
LIMIT 5 OFFSET 5;

Output:

title
Monsters University
Monsters, Inc.
Ratatouille
The Incredibles
Toy Story

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Key Takeaways

• DISTINCT removes duplicate values from results — useful when selecting a single column like a list of directors
• ORDER BY column ASC sorts A→Z or lowest→highest; DESC reverses it
• LIMIT n returns at most n rows; OFFSET n skips the first n rows before counting
• Combining ORDER BY + LIMIT + OFFSET is the standard pattern for pagination