试图在SQL中为表创建外键时出错？[副本]

Question

CREATE TABLE SCREEN(
BRANCHID CHAR(2) NOT NULL,
SCREENID CHAR(2) NOT NULL,
SCREENCACPACITY NUMBER(3),
CONSTRAINT SCREEN_PK PRIMARY KEY(BRANCHID, SCREENID),
CONSTRAINT SCREEN_FK FOREIGN KEY(BRANCHID) REFERENCES BRANCH(BRANCHID));

CREATE TABLE SESSIONS(
SESSIONID CHAR(4) NOT NULL,
BRANCHID CHAR(2) NOT NULL,
SCREENID CHAR(2) NOT NULL,
MOVIEID CHAR(2) NOT NULL,
SESSIONDATE DATE,
SESSIONPRICE NUMBER(4,2),
CONSTRAINT SESSIONS_PK PRIMARY KEY(SESSIONID),
CONSTRAINT SESSIONS_FK1 FOREIGN KEY(BRANCHID) REFERENCES BRANCH(BRANCHID),
CONSTRAINT SESSIONS_FK2 FOREIGN KEY(SCREENID) REFERENCES SCREEN(SCREENID),
CONSTRAINT SESSIONS_FK3 FOREIGN KEY(MOVIEID) REFERENCES MOVIE(MOVIEID));

分支和电影屏幕已经制作完成，或多或少与屏幕相同。帮助pl0x

Answer 1

大多数（如果不是全部）支持外键的SQL类型都将强制您将外键指向整个主键。在您的示例中，table SCREEN有(BRANCHID，SCREENID)作为PK，但您的SESSIONS_FK2 FK只指向SCREENID。

您应该创建一个指定这两个列的外键。类似于：

CONSTRAINT FK_SESSION_SCREEN FOREIGN KEY (BRANCHID, SCREENID) REFERENCES SCREEN(BRANCHID, SCREENID)

其他需要考虑的事项：