使用 Linq C# WPF 将两个表连接到一个数据网格中

Question

我想将两个 table 连接到一个数据网格中。 table 一：tblProjects - table 二：tblEmployeeLoginDetails

在这种方法中- private void FillProjectsDataGrid()我想使用这种编码来填充我的数据网格：

            dgViewProjects.ItemsSource = DC.tblProjects.Where<tblProject>(c => c.ProjectID != null)
                .Select<tblProject, ProjectData>(m => new ProjectData()
                {
                    ProjectID = m.ProjectID,
                    Name = m.ProjectName,
                    Status = m.ProjectStatus,
                    Employee = m.EmployeeName,
                });

            dgViewProjects.ItemsSource = DC.tblEmployeeLoginDetails.Where<tblEmployeeLoginDetail>(c => c.LoginID != null)
                .Select<tblEmployeeLoginDetail, EIDData>(m => new EIDData()
                {
                    UserID = m.LoginID,
                    Name = m.EmployeeName,
                    Surname = m.EmployeeSurname,
                    Email = m.EmployeeEmailAddress,
                    Password = m.EmployeePassword,
                    Role = m.RoleID.ToString(),
                    Department = m.EmployeeDepartment,
                    IDNumber = m.EmployeeIDNumber,
                    Gender = m.EmployeeGender,
                    Date = m.EmployeeDOB.Value,
                    HomeAddress = m.EmployeeHomeAddress,
                    Telephone = m.EmployeeTelephoneNumber,
                    City = m.EmployeeCity,
                    Province = m.EmployeeProvinceCode,
                    SetImage = m.EmployeeProfilePicture
                });

对于 tblProjects 我使用这个 class:

public struct PDData
{
    public string _project;

    public int ProjectID { get; set; }
    public string Name { get; set; }
    public string Status { get; set; }
    public string Employee { get; set; }
}

对于 tblEmployeeLoginDetails 我使用这个 class:

public struct EIDData
{
    public string _sts;

    public int UserID { get; set; }
    public string Name { get; set; }
    public string Surname { get; set; }
    public string Email { get; set; }
    public string Password { get; set; }
    public string Role { get; set; }
    public string Department { get; set; }
    public string IDNumber { get; set; }
    public string Gender { get; set; }
    public DateTime Date { get; set; }
    public string HomeAddress { get; set; }
    public string Telephone { get; set; }
    public string City { get; set; }
    public string Province { get; set; }
    public Binary SetImage { get; set; }
}

现在我想加入这两个 table 并在一个数据网格中显示信息。我尝试了 Linq 连接语句，但出现此错误：

An unhandled exception of type 'System.InvalidCastException' occurred in Haze.exe

Additional information: Unable to cast object of type 'System.Data.Linq.DataQuery1[Haze.tblProject]' to type 'System.Collections.Generic.List1[Haze.tblProject]'.

最后是我的加入编码：

        List<tblProject> Join = (List<tblProject>)from u in DC.tblEmployeeLoginDetails
                                                  join b in DC.tblProjects
                                                  on u.LoginID equals b.ProjectID
                                                  where b.ProjectID != null
                                                  select b;

我不知道如何使用我必须在一个数据网格中显示的 class 将这两个 table 连接在一起。如果有人有任何建议或帮助，请不要犹豫发表评论。谢谢！

Answer 1

你尝试了吗

    List<tblProject> Join = (from u in DC.tblEmployeeLoginDetails
                                      join b in DC.tblProjects
                                      on u.LoginID equals b.ProjectID
                                      where b.ProjectID != null
                                      select b).ToList();

Answer 2

这将为您提供一个新的匿名 class，其中包含您加入时的员工和项目详细信息。您的加入仅返回项目的值

    var Join = (from u in DC.tblEmployeeLoginDetails
                                              join b in DC.tblProjects
                                              on u.LoginID equals b.ProjectID
                                              where b.ProjectID != null
                                              select new {Project=a, Employee=b}).ToList();

然后你必须将它绑定到你的数据表，像这样：

    dgViewProjects.ItemsSource = Join;

您的第一个代码块将用第二个代码块覆盖数据源的初始设置，而不是添加到它。

使用 Linq C# WPF 将两个表连接到一个数据网格中

Joining two tables in one datagrid usig Linq C# WPF

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