How to query mysql pagination

MySQL is a commonly used relational database management system used to store and manage large amounts of data. In practical applications, it is often necessary to perform paging queries on data in the database in order to display part of the data on the user interface. This article will introduce how to use MySQL to perform paging queries.

1. Use the LIMIT keyword for paging queries

MySQL provides the LIMIT keyword to limit the number of query results returned. The LIMIT keyword can accept two parameters. The first parameter specifies the starting position of the query results, and the second parameter specifies the number of returned query results.

For example, suppose we have a table named "users" that stores a large amount of user data. We want to display 10 pieces of data per page and query the data on the second page. You can use the following SQL statement:

SELECT * FROM users LIMIT 10 OFFSET 10;

In the above SQL statement, LIMIT 10 means displaying 10 pieces of data per page, and OFFSET 10 means querying from The 11th piece of data in the result starts to be returned, that is, the data on the second page is returned.

2. Sort using the ORDER BY keyword

When performing paging queries, it is usually necessary to sort the query results so that they can be displayed according to specific conditions. MySQL provides the ORDER BY keyword for sorting query results.

For example, if we want to sort in descending order according to the user's registration time and query the data on the second page, we can use the following SQL statement:

SELECT * FROM users ORDER BY register_time DESC LIMIT 10 OFFSET 10;

In the above SQL statement, ORDER BY register_time DESC Indicates sorting in descending order according to registration time, LIMIT 10 OFFSET 10 means that 10 pieces of data are displayed on each page, and the return starts from the 11th piece of data, that is, the data of the second page is returned.

3. Use the COUNT function to obtain the total number of records

When performing paging queries, you usually need to know how many records there are in total in order to calculate the total number of pages and generate paging navigation. MySQL provides the COUNT function to obtain the total number of records in the query results.

For example, if we want to query the total number of records in the user table, we can use the following SQL statement:

SELECT COUNT(*) FROM users;

In the above SQL statement, COUNT(*) represents the total number of records in the query result.

4. Calculate the total number of pages and generate paging navigation

After obtaining the total number of records, you can calculate the total number of pages based on the number displayed on each page and generate the corresponding Paginated navigation.

Assume that we have obtained a total number of records of 100, and each page displays 10 pieces of data. You can use the following PHP code to calculate the total number of pages and generate paging navigation:

$total_records = 100; $records_per_page = 10; $total_pages = ceil($total_records / $records_per_page); for ($i = 1; $i <= $total_pages; $i++) { echo "$i "; }

In the above PHP code , $total_records represents the total number of records, $records_per_page represents the number displayed on each page, and $total_pages represents the total number of pages. Use a for loop to traverse each page and generate corresponding paging navigation.

Summary:

This article introduces how to use MySQL for paging queries. Limit the number of query results returned by using the LIMIT keyword and ORDER BY keyword sorts the query results, uses the COUNT function to obtain the total number of records, calculates the total number of pages and generates paging navigation, which can realize paging display of data in the database. These methods are very useful in practical applications and can improve user experience and system performance. .

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