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HomeDatabaseMysql Tutorial数据操纵语言中数据的操作

--表数据的操作 --输入数据 select * from 学生 --说明 :用在insert与表名之间的into是一个可选关键字 insert into 学生 (学号,姓名,性别,年龄,专业) values ('003','杨丽','女',18,'计科') insert into 学生 (学号,姓名,性别,年龄,专业) values ('004','杨

   --表数据的操作

  --输入数据

  select * from 学生

  --说明 :用在insert与表名之间的into是一个可选关键字

  insert into 学生 (学号,姓名,性别,年龄,专业)

  values ('003','杨丽','女',18,'计科')

  insert into 学生 (学号,姓名,性别,年龄,专业)

  values ('004','杨丽','女',18,'计科')

  delete 学生 where 学号 = '004'

  alter table 学生

  add constraint ck check( 性别 in ( '男' ,'女'))

  insert into 学生

  (学号,姓名,性别,年龄,专业)

  values ('005','张三','男',18,'网络工程')

  --修改表中的数据

  --数据操纵语言中修改数据即是更新数据用update关键字

  /*

  语法表示为:

  update 表名

  set 列名 = 新数据

  where 条件表达式

  */

  use test

  go

  alter table 学生

  add 备注 char(20)

  update 学生

  set 性别 = '已毕业'

  --根据条件跟新数据

  update 学生

  set 备注 = '在读生'

  where 姓名 = '王芳'

  --删除数据

  --每次删除一行记录

  /*

  语法结构

  deleted 表名

  where 条件表达式

  */

  delete 学生

  where 学号 = '005'

  --一次性删除表的所有记录 :清空表格

  --有两种方法

  --其中方法二更快

  --方法一;

  delete 选课

  --方法二:

  truncate table 选课

  //

  --删除表

  drop table hh

  //

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