Question

我在为项目设置数据库时遇到了一些麻烦。我在我的表中插入语句，以便填充数据库。＆＃34; 但是，如果向下滚动到我的创建表的底部，您将看到＆＃34; Location_Address_Pickup＆＃34;和＆＃34; Location_Address_Drop＆＃34;两个参考＆＃34;地址＆＃34;在我的位置表。但是我需要这两个属性才能拥有自己的值，当他们引用相同的东西时我无法做到这一点。我应该将这些引用到别的东西来实现这个目标吗？我不明白这是怎么可能的..

Picture of my ERD

CREATE TABLE Customer (
CustomerID INT AUTO_INCREMENT,
Name VARCHAR(90) NOT NULL,
Phone VARCHAR(45) NULL,
PRIMARY KEY (CustomerID));

CREATE TABLE Location (
Address VARCHAR(100) NOT NULL,
Latitude VARCHAR(45) NOT NULL DEFAULT ' ',
Longitude VARCHAR(45) NOT NULL,
PRIMARY KEY (Address));


CREATE TABLE Employee (
EmployeeID INT AUTO_INCREMENT,
Name VARCHAR(90) NOT NULL,
PRIMARY KEY (EmployeeID));


CREATE TABLE Truck (
LicensePlate CHAR(20) NOT NULL,
color VARCHAR(45) NULL,
capacity VARCHAR(45) NULL,
PRIMARY KEY (LicensePlate));

CREATE TABLE Shifts (
ShiftTime DATETIME NOT NULL,
PRIMARY KEY (ShiftTime));

CREATE TABLE EmployeeShifts (
DesiredShift DATETIME NOT NULL,
EmployeeWorking INT NULL,
DateOfShift DATE,
PRIMARY KEY(DesiredShift, EmployeeWorking),
FOREIGN KEY (EmployeeWorking) REFERENCES Employee(EmployeeID),
FOREIGN KEY (DesiredShift) REFERENCES Shifts(ShiftTime));

CREATE TABLE Reservation (
ReservNum INT NOT NULL,
ReserveDate DATE NULL,
PickupTime VARCHAR(45) NOT NULL,
NumOfPassengers INT NULL,
sheduledTime VARCHAR(45) NULL,
ActualPickupTime VARCHAR(45),
ActualTime VARCHAR(45),
SalaryEarned VARCHAR(10),
PricePaid VARCHAR(45),
HourlyRate DECIMAL(7,2) NOT NULL,
Customer_CustomerID INT,
Truck_LicensePlate char(20) NOT NULL,
Employee_EmployeeID_Driver INT,
Location_Address_Pickup VARCHAR(100),
Employee_EmployeeID_Passenger INT,
Location_Address_Drop VARCHAR(100),
PRIMARY KEY (ReservNum),
FOREIGN KEY (Customer_CustomerID) REFERENCES Customer (CustomerID),
FOREIGN KEY (Truck_LicensePlate) REFERENCES Truck (LicensePlate),
FOREIGN KEY (Employee_EmployeeID_Driver) REFERENCES Employee (EmployeeID),
FOREIGN KEY (Location_Address_Pickup) REFERENCES Location (Address),
FOREIGN KEY (Employee_EmployeeID_Passenger) REFERENCES Employee (EmployeeID),
FOREIGN KEY (Location_Address_Drop) REFERENCES Location (Address));

Answer 1

据我所知，有一个位置表格，其中包含所有地址，纬度和经度。因此，此位置表是一种主位置表，可以保存Pickup，Drop的位置，也可以是Employee的位置以及与应用程序相关的其他位置。

要回答您的问题，请使用提取和删除地址来更正主要密钥。您需要添加Drop＆amp;的位置条目。位置表中的提货。然后你可以在预订表

中插入一个地址作为Drop，另一个作为Pickup

当属性应该具有唯一值时，属性引用相同的东西

1 个答案: