Different MySQL paging implementations

What are the paging methods in MySQL, specific code examples are required

MySQL is a relational database management system. In order to improve query efficiency and reduce the amount of data transmission, paging query is a very common requirement. MySQL provides a variety of paging methods. These methods will be introduced in detail below and specific code examples will be provided.

1. Use the LIMIT clause for paging:
   The LIMIT clause is used to limit the number of rows returned in query results. It has two parameters. The first parameter specifies the starting offset position of the returned result (counting from 0), and the second parameter specifies the number of rows of the returned result.

For example, query the first 10 pieces of data in a certain table:

SELECT * FROM table_name LIMIT 10;

Query the 11th to 20th pieces of data in a certain table:

SELECT * FROM table_name LIMIT 10, 10;

This The method is simple and easy to use, but the efficiency is low when querying large amounts of data, because when MySQL executes a LIMIT query, it needs to first fetch all the rows that meet the conditions and then return the results in paging.

2. Paging using the OFFSET clause:
   The OFFSET clause is used to specify the offset position of the query results. It has only one parameter, which indicates the record from which the results will be returned.

For example, query the first 10 data in a table:

SELECT * FROM table_name OFFSET 0;

Query the 11th to 20th data in a table:

SELECT * FROM table_name OFFSET 10;

Similar As for the LIMIT clause, the OFFSET clause will also fetch all qualified rows before querying, so there are also efficiency issues when processing large amounts of data.

3. Use ROW_NUMBER() function for paging:
   ROW_NUMBER() function can assign a serial number to each row in the query results. When used with the LIMIT clause, paging queries can be implemented.

For example, to query the first 10 pieces of data in a certain table:

SELECT * FROM (
  SELECT *, ROW_NUMBER() OVER (ORDER BY column_name) AS row_num
  FROM table_name
) AS temp_table
WHERE row_num <= 10;

To query the 11th to 20th pieces of data in a certain table:

SELECT * FROM (
  SELECT *, ROW_NUMBER() OVER (ORDER BY column_name) AS row_num
  FROM table_name
) AS temp_table
WHERE row_num > 10 AND row_num <= 20;

Use When the ROW_NUMBER() function performs paging queries, MySQL will optimize internally and only fetch rows that meet the conditions, so it is more efficient when processing large amounts of data.

The above are the commonly used paging methods in MySQL. Choosing an appropriate method according to the actual situation can effectively improve query efficiency.

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