In mysql, you can query the 2nd to 4th data through the "LIMIT" keyword. The specific statement is "SELECT * FROM data table name LIMIT 1,3;". The query starts from the 2nd record. 3 records. The LIMIT keyword specifies which record the query results start to display and how many records are displayed in total.
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When there are tens of thousands of data in the data table, once Querying all the data in the table will reduce the speed of data return and put a lot of pressure on the database server. At this time, you can use the LIMIT keyword to limit the number of returned query results.
LIMIT is a special keyword in MySQL, which is used to specify which record the query results start to be displayed and how many records are displayed in total.
Specify the initial position
The LIMIT keyword can specify which record the query results should start displaying from and how many records should be displayed.
LIMIT The basic syntax format for specifying the initial position is as follows:
LIMIT 初始位置，记录数
Among them, "initial position" indicates which record to start displaying; "number of records" indicates which record to display number of items. The first record is at position 0 and the second record is at position 1. The subsequent records are deduced in sequence.
Note: The two parameters after LIMIT must be positive integers.
Example 1
In the tb_students_info table, use the LIMIT clause to return 3 records starting from the 2nd record. The SQL statement and running results are as follows.
mysql> SELECT * FROM tb_students_info LIMIT 1,3; +----+-------+---------+------+------+--------+------------+ | id | name | dept_id | age | sex | height | login_date | +----+-------+---------+------+------+--------+------------+ | 2 | Green | 3 | 23 | F | 158 | 2016-10-22 | | 3 | Henry | 2 | 23 | M | 185 | 2015-05-31 | | 4 | Jane | 1 | 22 | F | 162 | 2016-12-20 | +----+-------+---------+------+------+--------+------------+ 5 rows in set (0.00 sec)
As you can see from the results, this statement returns the next three records starting from the second record. The first number "1" after the LIMIT keyword means starting from line 2 (the recorded position starts from 0, and the position of line 2 is 1), and the second number 3 means the number of rows returned.
Do not specify the initial position
When the LIMIT keyword does not specify the initial position, records will be displayed starting from the first record. The number of records displayed is specified by the LIMIT keyword.
LIMIT The basic syntax format without specifying the initial position is as follows:
LIMIT 记录数
Among them, "number of records" indicates the number of displayed records. If the value of "Number of records" is less than the total number of query results, the specified number of records will be displayed starting from the first record. If the value of "Number of records" is greater than the total number of query results, all the queried records will be displayed directly.
Example
Display the first 8 rows of the query results of the tb_students_info table. The SQL statements and running results are as follows.
mysql> SELECT * FROM tb_students_info LIMIT 8; +----+-------+---------+------+------+--------+------------+ | id | name | dept_id | age | sex | height | login_date | +----+-------+---------+------+------+--------+------------+ | 1 | Dany | 1 | 25 | F | 160 | 2015-09-10 | | 2 | Green | 3 | 23 | F | 158 | 2016-10-22 | | 3 | Henry | 2 | 23 | M | 185 | 2015-05-31 | | 4 | Jane | 1 | 22 | F | 162 | 2016-12-20 | | 5 | Jim | 1 | 24 | M | 175 | 2016-01-15 | | 6 | John | 2 | 21 | M | 172 | 2015-11-11 | | 7 | Lily | 6 | 22 | F | 165 | 2016-02-26 | | 8 | Susan | 4 | 23 | F | 170 | 2015-10-01 | +----+-------+---------+------+------+--------+------------+ 4 rows in set (0.00 sec)
Only 8 records are displayed in the results, indicating that "LIMIT 8" limits the number of displayed records to 8.
LIMIT with one parameter specifies starting from the first row of the query result. The only parameter indicates the number of rows returned, that is, "LIMIT n" and "LIMIT 0, n" return the same result. LIMIT with two arguments returns a specified number of rows of data starting at any position.
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