Question

我有3张桌子

员工（ID，FirstName，LastName） - 我们拥有所有员工，包括经理等。

EmployeeRole（RoleID，Role） - 这里我们定义了员工的角色

项目（ProjectName，Manager，Employee，Date ..） - 这里是分配给所有员工的项目的详细信息。

在项目表中，我有像Emmployee，Manager这样的列，这两列都是Employee表的外键。问题是我输入像（名字，姓氏），我如何找到emplyee的id。或表结构是错误的？
当我尝试在项目表中插入数据时，EmployeeRole表也在更新。它不应该更新EMployeeRole表。它是一个主数据。

请建议我解决方案？

Answer 1

您的逻辑数据模型不正确（恕我直言）。

项目可以有很多员工。员工可以将一个或多个项目作为特定角色工作。

因此，在Employee和Project之间有多对多，交集表具有Role类型。

e.g。

CREATE TABLE [dbo].[Employee](
    [EmployeeID] [int] NOT NULL,
    [FirstName] [nvarchar](50) NOT NULL,
    [LastName] [nvarchar](50) NOT NULL,
    [RoleID] [int] NOT NULL,
 CONSTRAINT [PK_Employee] PRIMARY KEY CLUSTERED 
(
    [EmployeeID] ASC
)) 
GO

CREATE TABLE [dbo].[Project](
    [ProjectID] [int] NOT NULL,
    [ProjectName] [nvarchar](50) NOT NULL,
 CONSTRAINT [PK_Project] PRIMARY KEY CLUSTERED 
(
    [ProjectID] ASC
)) 
GO

CREATE TABLE [dbo].[ProjectEmployee](
    [ProjectID] [int] NOT NULL,
    [EmployeeID] [int] NOT NULL,
    [RoleID] [int] NOT NULL,
 CONSTRAINT [PK_ProjectEmployee] PRIMARY KEY CLUSTERED 
(
    [ProjectID] ASC,
    [EmployeeID] ASC,
    [RoleID] ASC
)) 
GO

CREATE TABLE [dbo].[Role](
    [RoleID] [int] NOT NULL,
    [RoleName] [int] NOT NULL,
 CONSTRAINT [PK_Role] PRIMARY KEY CLUSTERED 
(
    [RoleID] ASC
)) 
GO

ALTER TABLE [dbo].[ProjectEmployee]  WITH CHECK ADD  CONSTRAINT [FK_ProjectEmployee_Employee] FOREIGN KEY([EmployeeID])
REFERENCES [dbo].[Employee] ([EmployeeID])
GO

ALTER TABLE [dbo].[ProjectEmployee]  WITH CHECK ADD  CONSTRAINT [FK_ProjectEmployee_Project] FOREIGN KEY([ProjectID])
REFERENCES [dbo].[Project] ([ProjectID])
GO

ALTER TABLE [dbo].[ProjectEmployee]  WITH CHECK ADD  CONSTRAINT [FK_ProjectEmployee_Role] FOREIGN KEY([RoleID])
REFERENCES [dbo].[Role] ([RoleID])
GO

然后你的LinqToEntity看起来像这样：

// Add a new Role
Role role = new Role();
role.RoleID = 1;   // TODO: make identity in database
role.RoleName = "Role 1";
db.Roles.Add(role);
db.SaveChanges();

// Add a new Employee
Employee employee = new Employee();
employee.EmployeeID = 1;   // TODO: make identity in database
employee.FirstName = "Carl";
employee.LastName = "Prothman";
db.Employee.Add(employee);
db.SaveChanges();

// Add a new Project
Project project = new Project();
project.ProjectID = 1;   // TODO: make identity in database
project.ProjectName = "Create new data model";
db.SaveChanges();

// Add employee to project as role1
ProjectEmployee projectEmployee = new ProjectEmployee();
projectEmployee.ProjectID = project.ProjectID;
projectEmployee.EmployeeID = employee.EmployeeID;
projectEmployee.RoleID = role.RoleID;
db.ProjectEmployees.Add(projectEmployee);
db.SaveChanges();

处理实体框架中的主数据表和相关表

1 个答案: