LIMIT vs TOP vs FETCH FIRST syntax in SQL - Practice Questions

Challenge - 5 Problems

❓ query_result

intermediate

What does this SQL query return?

Consider a table Employees with columns id and name. What will this query return?

SELECT * FROM Employees LIMIT 3;

SQL

SELECT * FROM Employees LIMIT 3;

A All rows except the first 3

B The last 3 rows from Employees table

C An error because LIMIT is not valid SQL

D The first 3 rows from Employees table

💡 Hint

LIMIT is used to restrict the number of rows returned starting from the top.

LIMIT 3 returns the first 3 rows from the result set.

❓ query_result

intermediate

What is the output of this SQL Server query?

Given the same Employees table, what does this query return?

SELECT TOP 5 * FROM Employees;

SQL

SELECT TOP 5 * FROM Employees;

A The first 5 rows from Employees table

B The last 5 rows from Employees table

C Syntax error because TOP is not supported

D All rows except the first 5

💡 Hint

TOP is used in SQL Server to limit rows returned.

TOP 5 returns the first 5 rows from the Employees table.

📝 Syntax

advanced

Which query uses FETCH FIRST correctly?

Which of these queries correctly limits the result to 4 rows using FETCH FIRST syntax?

A SELECT * FROM Employees FETCH ONLY FIRST 4 ROWS;

B SELECT * FROM Employees FETCH FIRST 4 ROWS ONLY;

C SELECT * FROM Employees FETCH FIRST 4 ROWS;

D SELECT * FROM Employees FETCH 4 ROWS FIRST;

💡 Hint

The correct syntax is FETCH FIRST number ROWS ONLY.

Option B uses the correct standard syntax for FETCH FIRST.

🔧 Debug

advanced

Why does this query cause an error?

This query causes an error:

SELECT TOP FROM Employees;

What is the reason?

SQL

SELECT TOP FROM Employees;

A TOP requires a number to specify how many rows to return

B TOP cannot be used without ORDER BY clause

C TOP is not valid in SQL Server

D The table name is missing

💡 Hint

TOP must be followed by a number.

TOP keyword requires a number to specify the limit of rows.

🧠 Conceptual

expert

Which statement about LIMIT, TOP, and FETCH FIRST is true?

Choose the correct statement about LIMIT, TOP, and FETCH FIRST in SQL:

A FETCH FIRST is only used in MySQL

B LIMIT is standard SQL and works in all databases

C TOP is used mainly in SQL Server and requires a number after it

D All three keywords are interchangeable in any SQL database

💡 Hint

Think about which database uses TOP and what it requires.

TOP is specific to SQL Server and requires a number to limit rows.

Practice

1. Which SQL clause is used to limit the number of rows returned in a query in MySQL and PostgreSQL?

easy

A. LIMIT

B. TOP

C. FETCH FIRST

D. ROWNUM

Solution

1. Step 1: Identify the database systems mentioned

   MySQL and PostgreSQL use the LIMIT clause to restrict rows.

2. Step 2: Match the clause to the database

   TOP is for SQL Server, FETCH FIRST is for Oracle and others, ROWNUM is Oracle-specific but older style.

3. Final Answer:

   LIMIT -> Option A

4. Quick Check:

   MySQL/PostgreSQL use LIMIT [OK]

Hint: MySQL/PostgreSQL use LIMIT to restrict rows [OK]

Common Mistakes:

• Confusing TOP with LIMIT
• Using FETCH FIRST in MySQL
• Using ROWNUM in PostgreSQL

2. Which of the following is the correct syntax to get the top 5 rows in SQL Server?

easy

A. SELECT * FROM table WHERE ROWNUM <= 5;

B. SELECT * FROM table LIMIT 5;

C. SELECT * FROM table FETCH FIRST 5 ROWS ONLY;

D. SELECT TOP 5 * FROM table;

Solution

1. Step 1: Identify SQL Server syntax for limiting rows

   SQL Server uses TOP n after SELECT to limit rows.

2. Step 2: Check each option

   SELECT * FROM table LIMIT 5; uses LIMIT (MySQL/PostgreSQL), SELECT * FROM table FETCH FIRST 5 ROWS ONLY; uses FETCH FIRST (Oracle), SELECT * FROM table WHERE ROWNUM <= 5; uses ROWNUM (Oracle). Only SELECT TOP 5 * FROM table; is correct for SQL Server.

3. Final Answer:

   SELECT TOP 5 * FROM table; -> Option D

4. Quick Check:

   SQL Server uses TOP [OK]

Hint: TOP goes right after SELECT in SQL Server [OK]

Common Mistakes:

• Using LIMIT in SQL Server
• Placing TOP after FROM
• Using FETCH FIRST in SQL Server

3. Given this query in Oracle:

SELECT * FROM employees FETCH FIRST 3 ROWS ONLY;

What will be the result?

medium

A. Syntax error because FETCH FIRST is not valid in Oracle

B. Returns the first 3 rows from employees

C. Returns all rows because FETCH FIRST is ignored

D. Returns 3 random rows from employees

Solution

1. Step 1: Understand FETCH FIRST in Oracle

   Oracle supports FETCH FIRST n ROWS ONLY to limit rows returned.

2. Step 2: Determine query behavior

   The query returns exactly the first 3 rows from the employees table as ordered by the query (default order if none specified).

3. Final Answer:

   Returns the first 3 rows from employees -> Option B

4. Quick Check:

   Oracle FETCH FIRST limits rows [OK]

Hint: FETCH FIRST limits rows in Oracle [OK]

Common Mistakes:

• Thinking FETCH FIRST causes syntax error in Oracle
• Assuming FETCH FIRST returns random rows
• Believing FETCH FIRST is ignored

4. Identify the error in this SQL Server query:

SELECT * FROM customers FETCH FIRST 10 ROWS ONLY;

medium

A. Should use LIMIT instead of FETCH FIRST

B. Missing ORDER BY clause with FETCH FIRST

C. FETCH FIRST is not supported in SQL Server

D. Syntax is correct, no error

Solution

1. Step 1: Check FETCH FIRST support in SQL Server

   SQL Server does not support FETCH FIRST; it uses TOP instead.

2. Step 2: Analyze other options

   Missing ORDER BY clause with FETCH FIRST is incorrect because FETCH FIRST requires ORDER BY in some databases but SQL Server does not support FETCH FIRST at all. Should use LIMIT instead of FETCH FIRST is wrong because SQL Server uses TOP, not LIMIT. Syntax is correct, no error is false because syntax is invalid.

3. Final Answer:

   FETCH FIRST is not supported in SQL Server -> Option C

4. Quick Check:

   SQL Server uses TOP, not FETCH FIRST [OK]

Hint: SQL Server uses TOP, not FETCH FIRST [OK]

Common Mistakes:

• Using FETCH FIRST in SQL Server
• Confusing LIMIT with FETCH FIRST
• Assuming FETCH FIRST works without ORDER BY

5. You want to write a query that returns the top 10 rows from a table named sales in a database that supports both FETCH FIRST and LIMIT. Which query is correct and why?

Options:
A) SELECT * FROM sales LIMIT 10;
B) SELECT * FROM sales FETCH FIRST 10 ROWS ONLY;
C) SELECT TOP 10 * FROM sales;
D) SELECT * FROM sales WHERE ROWNUM <= 10;

hard

A. Correct if the database supports LIMIT syntax

B. Correct if the database supports FETCH FIRST syntax

C. Correct only in SQL Server

D. Correct only in Oracle with ROWNUM

Solution

1. Step 1: Understand the database supports both FETCH FIRST and LIMIT

   Some modern databases like DB2 or Oracle 12c+ support FETCH FIRST, while others like MySQL use LIMIT.

2. Step 2: Choose the correct syntax for the database

   If the database supports both, FETCH FIRST is the ANSI standard and preferred for portability. LIMIT is not standard SQL. TOP is SQL Server specific, and ROWNUM is Oracle-specific older syntax.

3. Final Answer:

   SELECT * FROM sales FETCH FIRST 10 ROWS ONLY; -> Option A

4. Quick Check:

   FETCH FIRST is ANSI standard for limiting rows [OK]

Hint: Use FETCH FIRST for ANSI standard row limiting [OK]

Common Mistakes:

• Using TOP in non-SQL Server databases
• Assuming LIMIT is standard SQL
• Using ROWNUM outside Oracle