mysql-3数据库与数据表操作
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1.我发现我以前创建的数据表没有主键名称,现在要修改结构,并设置一个自动编号的id
(1)先清除原来的记录
mysql> deletefrom user_info;
Query OK, 1 rowaffected (0.02 sec)
mysql> select *from user_info;
Empty set (0.00sec)
没有记录啦
(2)再添加主键
mysql> altertable user_info add primary key(id);
Query OK, 0 rowsaffected (0.06 sec)
Records: 0 Duplicates: 0 Warnings: 0
(3)添加自动编号的功能
mysql> altertable user_info modify id int unique auto_increment;
Query OK, 0 rowsaffected (0.04 sec)
Records: 0 Duplicates: 0 Warnings: 0
成功啦
2.对数据表stu_info进行同样的操作
下面进行三步走:
先看看原来的样子
mysql> deletefrom stu_info;
Query OK, 3 rowsaffected (0.00 sec)
mysql> altertable stu_info add primary key(id);
Query OK, 0 rowsaffected (0.03 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> altertable stu_info modify id int unique auto_increment;
Query OK, 0 rowsaffected (0.03 sec)
Records: 0 Duplicates: 0 Warnings: 0
成功啦;
3.下面为两个数据表进行添加记录
(1)user_info添加多条记录:
mysql> insert into user_infovalues(null,"yhd","yhd",1),(null,"root","root",0),(null,"xiaodao","xiaodao",0);
Query OK, 3 rows affected (0.00 sec)
Records: 3 Duplicates: 0 Warnings: 0
mysql> select *from user_info;
一次添加三个记录
mysql> insertinto stu_info values(null,"杨过",120,120,120),(null,"小龙女",110,110,110),(null,"黄蓉",80,120,100),(null,"李莫愁",90,100,110);
Query OK, 4 rows affected(0.01 sec)
Records: 4 Duplicates: 0 Warnings: 0
mysql> select *from stu_info;
一次添加4个记录
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好啦,今天就学习到这里啦,
今天学习了,清除记录,修改主键,修改索引值,修改自动编号的id,添加多条记录;