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How to delete data in mysql

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May 17, 2019 am 11:25 AM

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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:

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

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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)

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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)

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

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