sql example 7 – delete

sql example 7 – delete

• sql create
• sql insert

delete from user1 where id=99;

select * from user1;

| id | username |
+----+----------+
|  1 | user1    |
|  2 | user2    |
|  3 | user3    |
| 99 | I am 99  |

delete from user1 where id=99;

select * from user1;

| id | username |
+----+----------+
|  1 | user1    |
|  2 | user2    |
|  3 | user3    |

删除表中全部的数据

delete from user1;

delete from user1;

select * from user1;
Empty set (0.00 sec)

使用 delete 的时候最后先用 select 看下

select * from .. 的结果就是 delete from ... 执行的时候被删除的东向

清空一个表是使用 truncate table user1 等价上面的 delete from user1
删除一个表是使用 drop table tablename
删除一个数据库使用 drop database databasename