Question

create table assigned(
        num int,
        tripdate date,
        PRIMARY KEY(num),
        FOREIGN KEY(num) REFERENCES seats(num),
        FOREIGN KEY(tripdate) REFERENCES trip(tripdate)
);

create table trip(
        num int,
        tripdate date,
        meal varchar(50),
        PRIMARY KEY(num,tripdate),
        FOREIGN KEY(num) REFERENCES ticket(num)
);

create table seats(
        aircraft_seats_id varchar(50),
        num int,
        class varchar(50),
        PRIMARY KEY(aircraft_seats_id,num), 
        FOREIGN KEY(aircraft_seats_id) REFERENCES aircraft(crafts_id)
);

创建桌子座位（ aircraft_seats_id varchar（50）， num int， varchar（50）类，主键（aircraft_seats_id，num），外键（aircraft_seats_id）参考飞机（crafts_id））;

分配的表中存在错误，无法添加外键约束

Answer 1

您的陈述中有错字。您不能为主键和外键分配相同的名称。注意：外键只是引用另一个表中的主键。

无法在已分配的表中添加外键约束

1 个答案: