CREATE TABLE Teacher

   (

         Id      INT IDENTITY(1,1) NOT NULL    PRIMARY KEY,

         Name    VARCHAR(10)    NOT NULL,

   );

   CREATE TABLE Student

   (

         Id        INT IDENTITY(1,1) NOT NULL PRIMARY KEY,

         TeacherID    INT NOT NULL FOREIGN KEY REFERENCES Teacher(Id),

         Name    VARCHAR(10)    NOT NULL,

         Age        INT    NOT NULL,

   );

   --方法一:

   INSERT INTO Teacher (Name) VALUES('李老师')

   --方法二: 跟方法一相比少了INTO; INTO可有可无

   INSERT Teacher (Name) VALUES('陈老师')

   --方法三: 跟方法二相比秒了Teacher表的列名，如果不写则VALUES里的列值必须与Teacher表的列顺序一致(可为NULL的列如果为NULL也必须写NULL，不可以省掉)

   INSERT Teacher VALUES('谢老师')

   --一次性插入多条数据（效率比一条一条插入高）

   INSERT INTO Teacher VALUES('李老师'),('陈老师'),('谢老师');

 --删除Id为1的数据

   DELETE Teacher WHERE Id=1

   --删除整个表

   DELETE Teacher

  --要修改多个列则列与列之间用","间隔：UPDATE TABLE SET A='A', B= 'B'

   UPDATE Teacher SET Name='白老师' where Name='李老师'

  UPDATE Teacher SET Name= Name + ''

   SELECT * FROM Teacher

   SELECT Id, Name FROM Teacher WHERE Id < 3