LIMIT clause behavior in SQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the LIMIT clause do in an SQL query?

The LIMIT clause restricts the number of rows returned by a query to a specified maximum number.

beginner

How do you use LIMIT to get the first 5 rows of a table named 'employees'?

Use the query: SELECT * FROM employees LIMIT 5; This returns only the first 5 rows from the 'employees' table.

intermediate

What happens if you use LIMIT 0 in a query?

Using LIMIT 0 returns zero rows, meaning no data is returned from the query.

intermediate

How can you skip the first 10 rows and get the next 5 rows using LIMIT?

Use LIMIT 5 OFFSET 10. This skips the first 10 rows and returns the next 5 rows.

intermediate

Is the order of rows guaranteed when using LIMIT without ORDER BY?

No, without an ORDER BY clause, the order of rows returned with LIMIT is not guaranteed and can vary.

What does the SQL clause LIMIT 3 do?

A Deletes 3 rows from the table

B Skips the first 3 rows

C Returns all rows except the first 3

D Returns the first 3 rows of the query result

LIMIT 3 restricts the output to only the first 3 rows of the query result.

How do you get rows 6 to 10 from a table using LIMIT and OFFSET?

A LIMIT 6 OFFSET 10

B LIMIT 10 OFFSET 6

C LIMIT 5 OFFSET 5

D LIMIT 5 OFFSET 10

LIMIT 5 OFFSET 5 skips the first 5 rows and returns the next 5 rows, which are rows 6 to 10.

What happens if you run SELECT * FROM table LIMIT 0;?

A Returns no rows

B Returns the first row only

C Returns an error

D Returns all rows

LIMIT 0 returns zero rows, so no data is returned.

Which clause should you add to ensure consistent row order when using LIMIT?

A ORDER BY

B GROUP BY

C WHERE

D HAVING

ORDER BY defines the order of rows, ensuring LIMIT returns consistent results.

Can LIMIT be used without OFFSET?

A No, OFFSET is required

B Yes, OFFSET is optional

C Only in some databases

D Only with ORDER BY

OFFSET is optional; LIMIT alone returns the first N rows.

Explain how the LIMIT clause works and how it can be combined with OFFSET to paginate query results.

Think about showing pages of results, like pages in a book.

Describe why it is important to use ORDER BY with LIMIT when you want consistent results.

Imagine picking the first few items from a shuffled deck.

Practice

1. What does the LIMIT clause do in an SQL query?

easy

A. It restricts the number of rows returned by the query.

B. It sorts the rows in ascending order.

C. It groups rows based on a column.

D. It deletes rows from the table.

Solution

1. Step 1: Understand the purpose of LIMIT

   The LIMIT clause is used to restrict the number of rows returned by a query.

2. Step 2: Compare with other options

   Sorting is done by ORDER BY, grouping by GROUP BY, and deleting by DELETE statement, not LIMIT.

3. Final Answer:

   It restricts the number of rows returned by the query. -> Option A

4. Quick Check:

   LIMIT = restrict rows [OK]

Hint: LIMIT controls how many rows you get back [OK]

Common Mistakes:

• Confusing LIMIT with ORDER BY
• Thinking LIMIT deletes rows
• Mixing LIMIT with GROUP BY

2. Which of the following is the correct syntax to get the first 5 rows from a table named employees?

easy

A. SELECT * FROM employees LIMIT 5;

B. SELECT * FROM employees TOP 5;

C. SELECT * FROM employees FETCH FIRST 5 ROWS;

D. SELECT * FROM employees WHERE LIMIT = 5;

Solution

1. Step 1: Identify correct LIMIT syntax

   The standard SQL syntax to limit rows is using LIMIT followed by the number, e.g., LIMIT 5.

2. Step 2: Check other options

   TOP 5 is SQL Server syntax, FETCH FIRST 5 ROWS is standard SQL but typically requires 'ONLY', and WHERE LIMIT = 5 is invalid.

3. Final Answer:

   SELECT * FROM employees LIMIT 5; -> Option A

4. Quick Check:

   LIMIT 5 = first 5 rows [OK]

Hint: Use LIMIT number after FROM to restrict rows [OK]

Common Mistakes:

• Using TOP instead of LIMIT in standard SQL
• Misplacing LIMIT inside WHERE clause
• Using FETCH without OFFSET incorrectly

3. Given the table products with rows:
id | name
1 | Apple
2 | Banana
3 | Cherry
4 | Date
5 | Elderberry
What is the result of the query:
SELECT name FROM products ORDER BY id DESC LIMIT 3;?

medium

A. ["Apple", "Banana", "Cherry"]

B. ["Elderberry", "Date", "Cherry"]

C. ["Cherry", "Date", "Elderberry"]

D. ["Date", "Elderberry", "Cherry"]

Solution

1. Step 1: Understand ORDER BY id DESC

   Ordering by id descending means rows are sorted from highest id to lowest: 5,4,3,2,1.

2. Step 2: Apply LIMIT 3

   LIMIT 3 returns the first 3 rows after sorting: ids 5,4,3 which correspond to Elderberry, Date, Cherry.

3. Final Answer:

   ["Elderberry", "Date", "Cherry"] -> Option B

4. Quick Check:

   ORDER BY DESC + LIMIT 3 = top 3 highest ids [OK]

Hint: ORDER BY DESC then LIMIT gets top N rows [OK]

Common Mistakes:

• Ignoring ORDER BY and taking first rows as is
• Mixing ascending and descending order
• Confusing LIMIT number with offset

4. What is wrong with this query?
SELECT * FROM orders LIMIT;

medium

A. LIMIT only works with numeric columns.

B. LIMIT cannot be used without ORDER BY.

C. LIMIT must be placed before FROM clause.

D. LIMIT requires a number to specify how many rows to return.

Solution

1. Step 1: Check LIMIT syntax

   LIMIT must be followed by a number indicating how many rows to return.

2. Step 2: Validate other options

   LIMIT can be used without ORDER BY, it comes after FROM, and works on any query regardless of column types.

3. Final Answer:

   LIMIT requires a number to specify how many rows to return. -> Option D

4. Quick Check:

   LIMIT needs a number [OK]

Hint: Always put a number after LIMIT [OK]

Common Mistakes:

• Omitting the number after LIMIT
• Thinking ORDER BY is mandatory with LIMIT
• Placing LIMIT before FROM

5. You want to show page 3 of a product list, showing 10 products per page, ordered by price ascending. Which query correctly uses LIMIT and OFFSET to achieve this?

hard

A. SELECT * FROM products ORDER BY price ASC LIMIT 10 OFFSET 30;

B. SELECT * FROM products ORDER BY price ASC LIMIT 30 OFFSET 10;

C. SELECT * FROM products ORDER BY price ASC LIMIT 10 OFFSET 20;

D. SELECT * FROM products ORDER BY price ASC LIMIT 20 OFFSET 10;

Solution

1. Step 1: Calculate OFFSET for page 3 with 10 rows per page

   Page 1 shows rows 0-9, page 2 shows 10-19, so page 3 starts at offset 20.

2. Step 2: Use LIMIT 10 to get 10 rows for the page

   LIMIT 10 returns 10 rows starting from OFFSET 20.

3. Final Answer:

   SELECT * FROM products ORDER BY price ASC LIMIT 10 OFFSET 20; -> Option C

4. Quick Check:

   Page 3 offset = (3-1)*10 = 20 [OK]

Hint: OFFSET = (page-1)*rows, LIMIT = rows per page [OK]

Common Mistakes:

• Using wrong OFFSET calculation
• Mixing LIMIT and OFFSET values
• Forgetting ORDER BY for consistent paging