How to delete data in mysql

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

Delete data in a single table

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

DELETE FROM  [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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