刪除外鍵條目的步驟

Question

我有兩個表 Employee 和 Address。 Employee 是我的主表，Address 是透過外鍵 AddressId 與 Employee 關聯的子表。

當我刪除 Employee 記錄時，來自 Address 的記錄不會被刪除。我如何重寫我的程式碼來做到這一點？

Employee:
  [Id](Primary Key)
  [FirstName] 
  [LastName]
  [Email]
  [AddressId] (Foreign Key -> Address.Id)
  [Code]

Address:
  [Id] (Primary Key)
  [Details]
  [State]
  [Country]

這是我目前的程式碼：

public bool DeleteEmployee(int id)
{
            using (var context=new EmployeeDBEntities())
            {
                var employee = context.Employee.FirstOrDefault(x => x.Id == id);
               
                if (employee != null)
                {
                    context.Employee.Remove(employee);
                    context.SaveChanges();
                    return true;
                }
                return false;
            }
        }

Answer 1

您正在尋找 ON DELETE CASCADE 功能，該功能將向 MySQL 指示當刪除其「父」記錄（在另一個表中）時應刪除該記錄。

類似這樣的事情：

CREATE TABLE address (
    Id INT PRIMARY KEY AUTO_INCREMENT,
    Details VARCHAR(255) NOT NULL,
    State VARCHAR(255) NOT NULL,
    Country VARCHAR(255) NOT NULL
);

CREATE TABLE employee (
    Id INT PRIMARY KEY AUTO_INCREMENT,
    FirstName VARCHAR(255) NOT NULL,
    LastName VARCHAR(255) NOT NULL,
    Email VARCHAR(255) NOT NULL,
    AddressId INT NOT NULL,
    Code VARCHAR(255) NOT NULL,
    FOREIGN KEY (AddressId)
        REFERENCES address (Id)
        ON DELETE CASCADE
);