首先查询联接表 c# 代码

Question

我有这些 table我使用代码优先方法在 c# 中制作的。

员工class：

public int id { get; set; }
public string name { get; set; }

部门class：

public int id { get; set; }
public string deptName { get; set; }
public IQueryable<Employee> { get; set; }

这会在我的 sql 数据库中的我的员工 table 中生成一个 DepartmentID。但是我无法在 c# 中访问此字段，因为 DepartmentID 不是员工 class/model.

中的字段

我的问题是如何访问这个变量。我想做一些不同的连接等，但正在努力解决这个问题。

Answer 1

当然可以expose the foreign key，但不一定需要。 EF 的美妙之处在于您不需要联接。

首先我会清理你的类:

public class Employee
{
    public int ID { get; set; }
    public string Name { get; set; }

    // Exposed FK. By convention, EF know this is a FK.
    // EF will add one if you omit it.
    public int DepartmentID { get; set; }  
    // Navigation properties are how you access the related (joined) data
    public virtual Department Department { get; set; }  
}

public class Department
{
    public int ID { get; set; }
    public string Name { get; set; }

    public virtual ICollection<Employee> Employees { get; set; }
}

现在您可以轻松查询您的数据了：

var employeeWithDepartment = context.Employee
      .Include(e => e.Department)
      .FirstOrDefault(e => e.ID = 123);

var employeeName = employeeWithDepartment.Name;
var departmentName = employeeWithDepartment.Department.Name;
... etc.

var departmentWithListOfEmployees = context.Departments
     .Include(d => d.Employees)
     .Where(d => d.Name == "Accounting")
     .ToList();

... build table or something
foreach (var employee in departmentWithListOfEmployees.Employees)
{
     <tr><td>@employee.ID</td><td>@employee.Name</td>
}
... close table

首先查询联接表 c# 代码

Query joined tables c# code first

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