PSQL错误：对于引用表“锦标赛”的给定键，没有唯一约束匹配

Question

我有以下表格：

CREATE TABLE player (
playerID    INT,
name        VARCHAR(255) NOT NULL,
gender      CHAR(1) CHECK (gender IN ('M','F')) NOT NULL,
dob         DATE NOT NULL,
address     VARCHAR(255),
telNo       VARCHAR(20),
NHSNo       VARCHAR(12),
PRIMARY KEY (playerID),
UNIQUE (NHSNo)
);

CREATE TABLE stadium (
stadiumID   INT,
name        VARCHAR(255) NOT NULL,
address     VARCHAR(255) NOT NULL,
telNo       VARCHAR(20) NOT NULL,
PRIMARY KEY (stadiumID)
);

CREATE TABLE tournament (
onDate      DATE,
result      VARCHAR(4) CHECK (result IN ('Win','Lose')),
stadiumID   INT NOT NULL,
PRIMARY KEY (onDate, stadiumID),
FOREIGN KEY (stadiumID) REFERENCES stadium (stadiumID),
UNIQUE (onDate, coachID)
);

每当我执行下面的表时，都会给出错误。 :(我不明白它有什么问题。

CREATE TABLE playTour (
playerID    INT NOT NULL,
onDate      DATE NOT NULL,
stadiumID   INT NOT NULL,
PRIMARY KEY (playerID, onDate, stadiumID),
FOREIGN KEY (playerID) REFERENCES player (playerID),
FOREIGN KEY (stadiumID) REFERENCES stadium (stadiumID),
FOREIGN KEY (onDate) REFERENCES tournament (onDate)
);

正是这一点导致了它：

FOREIGN KEY (onDate) REFERENCES tournament (onDate)
);