SQL 增删改查 复习

 1   CREATE TABLE Teacher
 2   (
 3         Id      INT IDENTITY(1,1) NOT NULL    PRIMARY KEY,
 4         Name    VARCHAR(10)    NOT NULL,
 5   );
 6 
 7 
 8   CREATE TABLE Student
 9   (
10         Id        INT IDENTITY(1,1) NOT NULL PRIMARY KEY,
11         TeacherID    INT NOT NULL FOREIGN KEY REFERENCES Teacher(Id),
12         Name    VARCHAR(10)    NOT NULL,
13         Age        INT    NOT NULL,
14   );

1   --方法一:
2   INSERT INTO Teacher (Name) VALUES(‘李老师‘)
3   --方法二: 跟方法一相比少了INTO; INTO可有可无
4   INSERT Teacher (Name) VALUES(‘陈老师‘)
5   --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)
6   INSERT Teacher VALUES(‘谢老师‘)
7   --一次性插入多条数据（效率比一条一条插入高）
8   INSERT INTO Teacher VALUES(‘李老师‘),(‘陈老师‘),(‘谢老师‘);

1 --删除Id为1的数据 
2   DELETE Teacher WHERE Id=1
3   --删除整个表
4   DELETE Teacher

1  --要修改多个列则列与列之间用","间隔：UPDATE TABLE SET A=‘A‘, B= ‘B‘
2   UPDATE Teacher SET Name=‘白老师‘ where Name=‘李老师‘

1  UPDATE Teacher SET Name= Name + ‘1‘

1   SELECT * FROM Teacher
2 
3   SELECT Id, Name FROM Teacher WHERE Id < 3