[英]Dealing with Master data table and Related tables in Entity Framework
我有3张桌子
Employee(ID,FirstName,LastName)-我们拥有所有员工,包括经理等,
EmployeeRole(RoleID,Role)-在这里我们定义了员工的角色
Project(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Emmployee,Manager之类的列,这两列都是Employee表的外键。 问题是我输入了(Firstname,Lastname)之类的信息,我该如何找到emplyee的ID。 还是表结构错误?
当我尝试在项目表中插入数据时,EmployeeRole表也在更新。它不应更新EMployeeRole表。 它是一个主数据。
请建议我解决方案?
您的逻辑数据模型不正确(IMHO)。
一个项目可以有很多员工。 员工可以作为一个特定角色从事一个或多个项目。
因此,员工和项目之间的关系是很多的,交集表具有角色类型。
例如
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,您的LinqToEntity如下所示:
// 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();
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