1. 创建数据表P_list(误将death设置成了not null)

mysql> create table P_list

-> (name varchar(20) not null,

-> owner varchar(20),

-> species varchar(20) not null,

-> sex char(1) not null,

-> birth year not null,

-> death year not null);

Query OK, 0 rows affected (0.02 sec)

2. 修改death设置成可接受 not null

mysql> alter table P_list modify death year(4);

Query OK, 0 rows affected (0.09 sec)

Records: 0 Duplicates: 0 Warnings: 0

3. 录入数据

mysql> insert into P_list

-> (name,owner,species,sex,birth,death)

-> values

-> ('Fluffy','Harold','Cat','F',2003,2010),

-> ('Bowser','Diane','Dog','M',2003,2009);

Query OK, 2 rows affected (0.01 sec)

Records: 2 Duplicates: 0 Warnings: 0

mysql> insert into P_list

-> (name,owner,species,sex,birth)

-> values

-> ('Claws','Gwen','Cat','M',2004),

-> ('Buffy',null,'Dog','F',2009),

-> ('Fang','Benny','Dog','M',2000),

-> ('Chirpy',null,'Bird','F',2008);

Query OK, 4 rows affected (0.00 sec)

Records: 4 Duplicates: 0 Warnings: 0

4. 使用UPDATE语句将名称为Fang的狗的主人改为Brian。

mysql> update P_list

-> set owner='Brian'

-> where name='Fang';

Query OK, 1 row affected (0.01 sec)

Rows matched: 1 Changed: 1 Warnings: 0

5. 将没有主人的宠物的owner字段值都改为TBA。

mysql> update P_list

-> set owner='TBA'

-> where owner is null;

Query OK, 2 rows affected (0.01 sec)

Rows matched: 2 Changed: 2 Warnings: 0

6. 删除已经死亡的宠物记录。

mysql> delete from P_list where death is not null;

Query OK, 2 rows affected (0.00 sec)

7. 删除所有表中的记录。

mysql> delete from P_list;

Query OK, 4 rows affected (0.01 sec)