MYSQLc创建spj表这样写为什么报错？

Question

CREATE database spj;
CREATE TABLE S
  (SNO CHAR(10)PRIMARY KEY,
  SNAME CHAR(10),
  STATUS CHAR(10),
  CITY CHAR(10));

CREATE TABLE P
  (PNO CHAR(10)PRIMARY KEY,
  PNAME CHAR(10),
  WEIGHT SMALLINT);
  
 CREATE TABLE J
  (JNO CHAR(10)PRIMARY KEY,
  JNAME CHAR(10),
  CITY  CHAR(10)); 
  
  CREATE TABLE SPJ
  (SNO CHAR(10),
  PNO CHAR(10),
  JNO CHAR(10),
  QTY INT,
  PRIMARY KEY(SN0,PNO,JNO),
  FOREIGN KEY(SNO)REFERENCES S(SNO),
  FOREIGN KEY(PNO)REFERENCES P(PNO),
  FOREIGN KEY(JNO)REFERENCES J(JNO)

要求为每张表建立主键，为spj表建立数据

Answer 1

一个表主键只能有一个