1.先要给生产的表，创建一个状态列
mysql> alter table student add state enum('0','1') default '1';
2.插入数据
mysql> insert into student(sname,sage,sgender) values('t1',20,'f'), ('t2',17,'m'),('t3',18,'m');
mysql> insert into student(sname,sage,sgender) values('t4',20,'f'), ('t5',17,'m'),('t6',18,'m');
3.删除数据 (把状态列改变为0)
mysql> update student set state='0' where sid=6;
4.查询数据 （生产中查询语句添加where条件，只查询state='1'的，这样等于0的就不会显示，达到伪删除的目的。）
mysql> select * from student where state='1';
+------------+-------+------+---------+---------------------+-------+
| sid | sname | sage | sgender | cometime | state |
+------------+-------+------+---------+---------------------+-------+
| 0000000001 | t1 | 20 | f | 2019-12-14 17:21:31 | 1 |
| 0000000002 | t2 | 17 | m | 2019-12-14 17:21:31 | 1 |
| 0000000003 | t3 | 18 | m | 2019-12-14 17:21:31 | 1 |
| 0000000004 | t4 | 20 | f | 2019-12-14 17:21:45 | 1 |
| 0000000005 | t5 | 17 | m | 2019-12-14 17:21:45 | 1 |
+------------+-------+------+---------+---------------------+-------+