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How to delete data in mysql

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2019-05-17 11:25:0022839browse

In MySQL, you can use the DELETE statement to delete one or more rows of data in a table.

How to delete data in mysql

Delete data in a single table

Use the DELETE statement to delete data from a single table. The syntax format is:

DELETE FROM <表名> [WHERE 子句] [ORDER BY 子句] [LIMIT 子句]

The syntax is as follows:

  • : Specify the name of the table to delete data.

  • ORDER BY clause: Optional. Indicates that when deleting, rows in the table will be deleted in the order specified in the clause.

  • WHERE clause: Optional. Indicates that the deletion conditions are limited for the deletion operation. If this clause is omitted, it means that all rows in the table are deleted.

  • LIMIT clause: Optional. Used to tell the server the maximum number of rows to be deleted before the control command is returned to the client.

  • Note: When the WHERE condition is not used, all data will be deleted.

    Delete all data in the table

    Delete all data in thetb_courses_new table. The input SQL statement and execution results are as follows.

    mysql> DELETE FROM tb_courses_new;
    Query OK, 3 rows affected (0.12 sec)
    mysql> SELECT * FROM tb_courses_new;
    Empty set (0.00 sec)

    Delete data in the table based on conditions

    In the tb_courses_new table, delete the record with course_id 4, enter the SQL statement and execute it The results are shown below.

    mysql> DELETE FROM tb_courses
        -> WHERE course_id=4;
    Query OK, 1 row affected (0.00 sec)
    mysql> SELECT * FROM tb_courses;
    +-----------+-------------+--------------+------------------+
    | course_id | course_name | course_grade | course_info      |
    +-----------+-------------+--------------+------------------+
    |         1 | Network     |            3 | Computer Network |
    |         2 | Database    |            3 | MySQL            |
    |         3 | Java        |            4 | Java EE          |
    +-----------+-------------+--------------+------------------+
    3 rows in set (0.00 sec)

    It can be seen from the running results that the record with course_id 4 has been deleted.

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