SQL TOP, LIMIT, FETCH FIRST Clause

SQL TOP, LIMIT, and FETCH FIRST clauses are used to retrieve a specific number of records from a table. These clauses are especially useful in large datasets with thousands of records.

Each of these SQL clauses performs a similar operation of limiting the results returned by a query, but different database management systems support them. In this article, we’ll explore the differences between these statements, provide syntax examples, and describe supporting databases.

SQL TOP, LIMIT, FETCH FIRST Clause

When working with large data sets in SQL, limiting the number of rows returned by a query can improve performance and make the data more manageable. The SQL SELECT TOP, LIMIT, and FETCH FIRST statements accomplish this purpose by limiting the result set to a specified number of row groups.

• SQL TOP Clause is used in SQL Server and Sybase to limit the number of records returned.
• SQL LIMIT Clause is utilized in MySQL, PostgreSQL, and SQLite.
• SQL FETCH FIRST Clause is part of the SQL standard and is supported by Oracle, DB2, PostgreSQL, and SQL Server (as part of OFFSET-FETCH).

Depending on the database management system (DBMS) being used, you can utilize the respective clause to efficiently manage data retrieval. This article will provide examples and guidance on how to use the SQL TOP, LIMIT, and FETCH FIRST clauses in different SQL environments.

SQL SELECT TOP Clause

The SELECT TOP clause in SQL only returns the specified number of rows from the table. It is valuable on enormous tables with a large number of records. Returning countless records can affect execution.

Note: Not all database systems support the SELECT TOP clause.

The SQL TOP keyword is utilized with these database systems:

• SQL Server
• MS Access 

Syntax:

SELECT column1, column2, ... TOP count
FROM table_name
[WHERE conditions]
[ORDER BY expression [ ASC | DESC ]];

Here,

• column1, column2 = names of columns
• count = number of records to be fetched
• WHERE conditions: Optional. Filters the data based on conditions.
• ORDER BY expression: Optional. Sorts the result set in ascending or descending order.

SQL SELECT TOP Clause Example

Let’s understand this using an example of SQL SELECT TOP statement.

We will use the following table for this example:

Write the following SQL queries to create this table

CREATE TABLE Employee (
   EmpId INTEGER PRIMARY KEY, 
   EmpName VARCHAR(225) NOT NULL,  
   Email VARCHAR(225) NOT NULL,   
   Address VARCHAR(225) NOT NULL,
   Age INT NOT NULL,
   Salary MONEY NOT NULL
);
INSERT INTO Employee (EmpId, EmpName, Email, Address, Age, Salary)
VALUES (1, 'Shubham', '[email protected]', 'India', 23, 50000.00),
       (2, 'Aman', '[email protected]', 'Australia', 21, 45000.00),
       (3, 'Naveen', '[email protected]', 'Sri Lanka', 24, 55000.00),
       (4, 'Aditya', '[email protected]', 'Austria', 21, 42000.00),
       (5, 'Nishant Saluja', '[email protected]', 'Spain', 22, 48000.00);

Example 1: Using SELECT TOP Clause in SQL

In this example, we will fetch the top 4 rows from the table.

Query:

SELECT TOP 4*
FROM Employee;

Output:

Example 2: SQL SELECT TOP with ORDER BY Clause

In this example, we will use the SQL SELECT TOP clause with ORDER BY clause to sort the data in the results set.

Query

SELECT TOP 4*
FROM Employee
ORDER BY Salary DESC;

Output:

Example 3: SQL SELECT TOP Clause with WHERE Clause Example

In this example, we will use the SELECT TOP clause with WHERE clause to filter data on specific conditions

Query: 

SELECT TOP 2*
FROM Employee
WHERE Salary>2000
ORDER BY Salary;

Output:

The above query will select all the employees according to the given condition (i.e. all Employees except the employee whose salary is less than 2000 will be selected) then the result will be sorted by Salary in ascending order (The ORDER BY keyword sorts the records in ascending order by default). Finally, the first 2 rows would be returned by the above query.

Example 4: SQL SELECT TOP PERCENT Clause Example

The PERCENT keyword is utilized to select the primary and percent of all-out rows. For example,

Query:

SELECT TOP 50 PERCENT*
FROM Employee;

Output:

Here, the above query will select the first 50% of employee records out of the total number of records(i.e., the first 3 rows will be returned). 

Example 5: SQL TOP PERCENT with WHERE Clause Example

We can also include some situations using the TOP PERCENT with the WHERE clause in the above query.

Query:

SELECT TOP 50 PERCENT*
FROM Employee
WHERE Salary<50000;

Output:

The above query will select the Top 50% of the records out of the total number of records from the table according to the given condition such that it returns only the Top 50% of the records with the employee whose salary is less than 5000 (i.e, 2 rows will be returned)

SQL LIMIT  Clause

SQL LIMIT Clause limits the number of results returned in the results set. The LIMIT Clause is utilized with the accompanying database systems:

• MySQL
• PostgreSQL
• SQLite

SQL LIMIT Clause Example

Since the LIMIT Clause is not supported in SQL Server we need to create a table in MySQL/PostgreSQL/SQLite. We will use the LIMIT clause in MySQL

CREATE TABLE Employee (
   EmpId INTEGER PRIMARY KEY, 
   EmpName VARCHAR(225) NOT NULL,  
   Email VARCHAR(225) NOT NULL,   
   Address VARCHAR(225) NOT NULL,
   Age INT NOT NULL,
   Salary MONEY NOT NULL
);

INSERT INTO Employee (EmpId, EmpName, Email, Address, Age, Salary)
VALUES (1, 'Shubham', '[email protected]', 'India', 23, 50000.00),
       (2, 'Aman', '[email protected]', 'Australia', 21, 45000.00),
       (3, 'Naveen', '[email protected]', 'Sri Lanka', 24, 55000.00),
       (4, 'Aditya', '[email protected]', 'Austria', 21, 42000.00),
       (5, 'Nishant Saluja', '[email protected]', 'Spain', 22, 48000.00);
    
SELECT * FROM Employee ;

Output:

Example 1: SELECT LIMIT Clause in SQL

In this example, we will use the SELECT LIMIT clause to display only 2 results.

Query:

SELECT * FROM Employee
WHERE Salary = 45000
LIMIT 2;

Output:

From the above query, the LIMIT operator limits the number of records to be returned. Here, it returns the first 2 rows from the table.

Example 2: SQL LIMIT with WHERE Clause

The accompanying query selects the initial 4 records from the Employee table with a given condition.

Query:

SELECT * FROM Employee
WHERE Salary = 45000
LIMIT 2;

Output:

The above query will select all the employees according to the imposed condition (i.e. it selects the limited 2 records from the table where salary is 2000). Finally, the first 2 rows would be returned by the above query.

Example 3: SQL LIMIT With OFFSET Clause

The OFFSET keyword is utilized to indicate beginning rows from where to select rows. For instance,

Query:

SELECT * FROM Employee
LIMIT 2 OFFSET 2;

Output:

Here, the above query selects 2 rows from the beginning of the third row (i.e., OFFSET 2 means, the initial 2 rows are excluded or avoided).

SQL FETCH FIRST Clause

SQL FETCH FIRST clause fetches the first given number of rows from the table. 

It is supported in database systems like:

• IBM DB2
• Oracle
• PostgreSQL

Syntax:

The syntax to use the FETCH FIRST clause in SQL is:

SELECT columns FROM table WHERE condition FETCH FIRST n ROWS ONLY;

Here,

• n: desired number of rows

Example 1: SQL FETCH FIRST Clause

We will use the same "Employee" table as used in previous examples.

FETCH FIRST clause in SQL Example

In this example, we will fetch the first 3 rows from the table.

Query:

SELECT * FROM Employee FETCH FIRST 3 ROWS ONLY;

Output:

Here, the above query will fetch the first 3 rows only from the table. We can also include some situations using the FETCH FIRST PERCENT and WHERE Clause in the above query.

Example 2: SQL FETCH FIRST PERCENT

In this example, we will fetch first 50% of the data from the table

Query:

SELECT *
FROM Employee
FETCH FIRST (SELECT CEIL(COUNT(*) / 2) FROM Employee) ROWS ONLY;

Output:

Here, the above query fetches the first 50% of the total number of rows (i.e., 2 rows) from the table.

Example 3: SQL FETCH FIRST with WHERE Clause

The "FETCH FIRST" syntax is not supported in MySQL. The correct syntax for limiting the number of rows in MySQL is by using the LIMIT clause.

Query:

SELECT *
FROM Employee
WHERE Salary = 45000
FETCH FIRST 1 ROW ONLY;

Output:

Here, the above query fetches the first 1 row from the table, with the condition that the salary is 45000 (i.e., it returns 1 row only).

Conclusion

SQL TOP, LIMIT and FETCH FIRST clause are used for a same purpose of limiting the data returned in results set. All three of these queries are not supported by all SQL DBMS. Each of them is supported by only some of the DBMS and depending on the DBMS you use, the query can differ.

We have explained all TOP, LIMIT and FETCH FIRST clause in SQL with examples, and also mentioned their supported DBMS to avoid confusion. Users should check if the clause is supported by their DBMS before using them.