In MySQL, you can use the DELETE statement to delete one or more rows of data in a table.
Delete data from 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 explained as follows:
<表名>: Specifies the name of the table whose data is to be deleted.ORDER BYClause: optional. Indicates that when deleting, each row in the table will be deleted in the order specified in the clause.WHEREClause: optional. Indicates that the deletion condition is limited for the deletion operation. If this clause is omitted, it means that all rows in the table are deleted.LIMITClause: optional. Used to tell the server the maximum number of rows to delete before control commands are returned to the client.
Note: When not using the WHERE condition, all data will be deleted.
Delete all data in the table
[Example 1] Delete all the data in the tb_courses_new table, the entered 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 from table based on condition
[Example 2] In the tb_courses_new table, delete the record whose course_id is 4, the input SQL statement and the execution result are as follows:
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.