What is the use of the database delete statement delete?

The database delete statement delete is used to delete one or more rows of data in a table. The syntax format is "DELETE FROM ccc43248daffbac9770dee47fdaff697 [WHERE clause] [ORDER BY clause] [LIMIT clause]"; When you do not use the WHERE clause to define the deletion conditions for the deletion operation, all data will be deleted.

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Delete statement delete

The DELETE statement can delete one or more rows of data in the table.

The syntax format is:

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

The syntax description is as follows:

• 722e3d59fd24604761db25f00f9b264f: 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 deleting all rows in the table.

• 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.

Example 1: Delete all data in the table

Delete all data in the tb_courses table

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

Example 2: Delete data in the table based on conditions

In the tb_students table, delete the record with id 4

mysql> DELETE FROM tb_students
    -> WHERE id=4;
Query OK, 1 row affected (0.00 sec)
mysql> SELECT * FROM tb_students;
+----+-------+---------+------+------+--------+------------+
| id | name  | dept_id | age  | sex  | height | login_date |
+----+-------+---------+------+------+--------+------------+
|  1 | Dany  |       1 |   25 | F    |    160 | 2015-09-10 |
|  2 | Green |       3 |   23 | F    |    158 | 2016-10-22 |
|  3 | Henry |       2 |   23 | M    |    185 | 2015-05-31 |
|  5 | Jim   |       1 |   24 | M    |    175 | 2016-01-15 |
|  6 | John  |       2 |   21 | M    |    172 | 2015-11-11 |
|  7 | Lily  |       6 |   22 | F    |    165 | 2016-02-26 |
|  8 | Susan |       4 |   23 | F    |    170 | 2015-10-01 |
+----+-------+---------+------+------+--------+------------+
4 rows in set (0.00 sec)

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

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