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 <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 the
tb_courses_newtable. 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)
Copy after loginDelete data in the table based on conditions
In the
tb_courses_newtable, 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)
Copy after loginIt can be seen from the running results that the record with course_id 4 has been deleted.
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