MySQL LIMIT
Summary: in this tutorial, you will learn how to use MySQL LIMIT
clause to constrain the number of rows returned by a query.
Introduction to MySQL LIMIT
clause
The LIMIT
clause is used in the SELECT
statement to constrain the number of rows to return. The LIMIT
clause accepts one or two arguments. The values of both arguments must be zero or positive integers.
The following illustrates the LIMIT
clause syntax with two arguments:
SELECT
select_list
FROM
table_name
LIMIT [offset,] row_count;
Code language: SQL (Structured Query Language) (sql)
In this syntax:
- The
offset
specifies the offset of the first row to return. Theoffset
of the first row is 0, not 1. - The
row_count
specifies the maximum number of rows to return.
The following picture illustrates the LIMIT
clause:
When you use the LIMIT
clause with one argument, MySQL will use this argument to determine the maximum number of rows to return from the first row of the result set.
Therefore, these two clauses are equivalent:
LIMIT row_count;
Code language: SQL (Structured Query Language) (sql)
And
LIMIT 0 , row_count;
In addition to the above syntax, MySQL provides the following alternative LIMIT
clause syntax:
LIMIT row_count OFFSET offset
Code language: SQL (Structured Query Language) (sql)
The LIMIT and ORDER BY clauses
By default, the SELECT
statement returns rows in an unspecified order. When you add the LIMIT
clause to the SELECT
statement, the returned rows are unpredictable.
Therefore, to ensure the LIMIT
clause returns an expected output, you should always use it with an ORDER BY
clause like this:
SELECT
select_list
FROM
table_name
ORDER BY
sort_expression
LIMIT offset, row_count;
Code language: SQL (Structured Query Language) (sql)
The following picture illustrates the evaluation order of the LIMIT
clause in the SELECT
statement:
MySQL LIMIT clause examples
We’ll use the customers
table from the sample database for demonstration.
1) Using MySQL LIMIT to get the highest or lowest rows
This statement uses the LIMIT
clause to get the top five customers who have the highest credit:
SELECT
customerNumber,
customerName,
creditLimit
FROM
customers
ORDER BY creditLimit DESC
LIMIT 5;
Code language: SQL (Structured Query Language) (sql)
In this example:
- First, the
ORDER BY
clause sorts the customers by credits in high to low. - Then, the
LIMIT
clause returns the first 5 rows.
Similarly, this example uses the LIMIT
clause to find five customers who have the lowest credits:
SELECT
customerNumber,
customerName,
creditLimit
FROM
customers
ORDER BY creditLimit
LIMIT 5;
Code language: SQL (Structured Query Language) (sql)
In this example:
- First, the
ORDER BY
clause sorts the customers by credits in low to high. - Then, the
LIMIT
clause returns the first 5 rows.
Because there are more than 5 customers that have credits zero, the result of the query above may lead to an inconsistent result.
To fix this issue, you need to add more columns to the ORDER BY
clause to constrain the row in unique order:
SELECT
customerNumber,
customerName,
creditLimit
FROM
customers
ORDER BY
creditLimit,
customerNumber
LIMIT 5;
Code language: SQL (Structured Query Language) (sql)
2) Using MySQL LIMIT clause for pagination
When you display data on the screen, you often want to divide rows into pages, where each page contains a limited number of rows like 10 or 20.
To calculate the number of pages, you take the total rows divided by the number of rows per page. For fetching rows of a specific page, you can use the LIMIT
clause.
This query uses the COUNT(*)
aggregate function to get the total rows from the customers
table:
SELECT
COUNT(*)
FROM
customers;
Code language: SQL (Structured Query Language) (sql)
+----------+
| COUNT(*) |
+----------+
| 122 |
+----------+
1 row in set (0.00 sec)
Code language: JavaScript (javascript)
Suppose that each page has 10 rows; to display 122 customers, you have 13 pages. The last 13th page contains two rows only.
This query uses the LIMIT
clause to get rows of page 1 which contains the first 10 customers sorted by the customer name:
SELECT
customerNumber,
customerName
FROM
customers
ORDER BY customerName
LIMIT 10;
Code language: SQL (Structured Query Language) (sql)
This query uses the LIMIT
clause to get the rows of the second page that include rows 11 – 20:
SELECT
customerNumber,
customerName
FROM
customers
ORDER BY customerName
LIMIT 10, 10;
Code language: SQL (Structured Query Language) (sql)
In this example, the clause LIMIT 10, 10
returns 10 rows for the row 11 – 20.
3) Using MySQL LIMIT to get the nth highest or lowest value
To get the nth highest or lowest value, you use the following LIMIT
clause:
SELECT select_list
FROM table_name
ORDER BY sort_expression
LIMIT n-1, 1;
Code language: SQL (Structured Query Language) (sql)
The clause LIMIT n-1, 1
returns 1
row starting at the row n
.
For example, the following finds the customer who has the second-highest credit:
SELECT
customerName,
creditLimit
FROM
customers
ORDER BY
creditLimit DESC
LIMIT 1,1;
Code language: SQL (Structured Query Language) (sql)
Let’s double-check the result. This query returns all customers sorted by credits from high to low:
SELECT
customerName,
creditLimit
FROM
customers
ORDER BY
creditLimit DESC;
Code language: SQL (Structured Query Language) (sql)
As you can see clearly from the output, the result was correct as expected.
Note that this technique works when there are no two customers who have the same credit limits. To get a more accurate result, you should use the DENSE_RANK()
window function.
MySQL LIMIT & DISTINCT clauses
If you use the LIMIT
clause with the DISTINCT
clause, MySQL immediately stops searching when it finds the number of unique rows specified in the LIMIT
clause.
The example uses the LIMIT
clause with the DISTINCT
clause to return the first five unique states in the customers
table:
SELECT DISTINCT
state
FROM
customers
WHERE
state IS NOT NULL
LIMIT 5;
Code language: SQL (Structured Query Language) (sql)
Summary
- Use the MySQL
LIMIT
clause to constrain the number of rows returned by theSELECT
statement.