Mac上设置环境变量PATH

0X01创建表

0x02列级约束

0x03注意点

2. 第二种

0x04数据结构

1x01完事具备只欠东风

1x02 例子

creat table S(
      SNO varchar(50) primary key,
      SNAME varchar(50) UNIQUE,
      status int ,
      City VARCHAR(50) );
  
creat table P(
    PNO varchar(50) primary key,
    PNAME varchar(50) ,
    color VARchar(50) ,
    weight varchar(50));
creat table J(
    JNO varchar(50) primary key,
    JNAME varchar(50) NOT NULL,
    city varchar(50));

creat table  SPJ(
    SNO varchar(50),
    PNO varchar(50),
    JNO varchar(50),
    QTY INT，
    primary key(SNO,PNO,JNO),
    foreign key(SNO) references S(SNO), 
    foreign key(PNO) references P(PNO),
    foreign key(JNO) references J(JNO));
    
    
  **插入数据:**
  

					
	insert into S values('S1','精益','20','天津'),
                    ('S2','盛锡','10','北京'),
					('S3','东方红','30','北京'),
					('S4','丰泰盛','20','天津'),
					('S5','为民','30','上海');
insert into P values('P1','螺母','红','12'),
                    ('P2','螺栓','绿','17'),
					('P3','螺丝刀','蓝','14'),
					('P4','螺丝刀','红','14'),
					('P5','凸轮','蓝','40'),
					('P6','齿轮','红','30');
insert into J values('J1','三建','北京'),
                    ('J2','一汽','长春'),
					('J3','弹簧厂','天津'),
					('J4','造船厂','天津'),
					('J5','机车厂','天津'),
					('J6','无线电厂','常州'),
					('J7','半导体厂','南京');
					
	insert into SPJ values('s1','p1','j1','200'),('s1','p1','j3','100'),('s1','p1','j4','700'),('s1','p2','j2','100'),('s2','p3','j1 ','400'),('s2','p3','j2','200'),('s2','p3','j4','500'),('s2','p3','j5','400'),('s2','p5','j1','400'),('s2','p5','j2','100'),('s3','p1','j1 ','200'),('s3','p3','j1','200'),('s4','p5','j1 ','100'),('s4','p6','j3','300'),('s4','p6','j4','200'),('s5','p2','j4','100'),('s5','p3','j1','200'),('s5','p6','j2','200'),('s5','p6','j4 ','500');