我觉得你把主键和外键列放错了，你也没有添加采购表的主键列

I think you misplaced the primary key and foreign key column also you didn't add Purchase table primary key column

CREATE TABLE Purchases 
(
ID INTEGER, -- Primary key column 
C_ID INTEGER,
GameName VARCHAR(30),
ConsoleType VARCHAR (20),
Price VARCHAR (254),
PaymentType VARCHAR (20),
Date TIMESTAMP,
PointsGained INTEGER,
PRIMARY KEY (ID),
FOREIGN KEY (C_ID) -- Replace ID with C_ID
    REFERENCES Customer(ID)  
);