MySQL中的多对多关系

Question

我有这种实体关系：

我想保存有关当前团队和最后一支队伍的信息，同时我也会保存每个团队的不同职位。

我创建了这个表：

玩家表：

create table player(

   codPlayer varchar(12) primary key,
   name varchar(30) unique not null,
   codCurrentTeam varchar(12),
   position varchar(20),
   foreign key (codCurrentTeam) references team(codTeam) 
);

团队表：

create table team(

   codTeam varchar(12) primary key,
   name varchar(40) unique not null

);

lastTeam表：

create table lastTeam(

    startDate date,
    finishDate date,
    codTeam varchar(12),
    codPlayer varchar(12),
    constraint pkLastTeam primary key (codTeam,codPlayer),
    foreign key (codTeam) references team(codTeam),
    foreign Key (codPlayer) references jugador (codPlayer)
);

职位表：

create table position(

   codPlayer varchar(12),
   codLastTeam varchar(24),
   position varchar(20),
   primary key (codPlayer, codLastTeam),
   foreign key (codPlayer) references jugador(codPlayer),
   foreign key (codLastTeam) references lastTeam(pkLastTeam)

);

我可以创建除position之外的所有表，mysql返回下一个错误：

  

错误代码：1215。无法添加外键约束

也许我的图有一些错误，但我不知道如何实现设计

Answer 1

问题是你没有

在lastTeam t中创建表位置“pkLastTeam”列

codPlayer varchar(12),
   codLastTeam varchar(24),
   position varchar(20),
   primary key (codPlayer, codLastTeam),
   foreign key (codPlayer) references jugador(codPlayer),
   foreign key (codLastTeam) references lastTeam(pkLastTeam)

);

Answer 2

我想我可以解决为 codTeam，codPlayer1 添加新的atributte codPlayer1 和更改 pkLastTeam 的问题。 表格看起来像这样：

create table position(

    codPlayer varchar(12),
    codTeam varchar(12),
    codPlayer1 varchar(12),
    position varchar(20),
    primary key (codPlayer, codTeam,codPlayer1),
    foreign key (codPlayer) references player(codPlayer),
    foreign key (codPlayer,codPlayer1) references lastTeam(codTeam,codPlayer)

);