LINQ左外連接排除

Question

我試圖排除第一個查詢的結果被包含在我的第二個查詢的結果中。

SQL等效於此處，其中A是我當前的查詢，B是舊查詢。

我一直在嘗試使用本指南進行左連接，但我似乎無法弄清楚它在我的情況下應該如何工作。 我只是不明白這應該如何工作（我不能讓語法突出顯示為快樂）。

var emp = from employee in empl
    join jc in jce on callout.job_class_code_fk equals jc.job_class_code_fk
    join av in ab on employee.employee_id_pk equals av.employee_id_fk
    join sh in sho on employee.employee_id_pk equals sh.employee_id_fk into lj
    from rnd2 in lj.DefaultIfEmpty()
    orderby employee.seniority descending
    select new
    {
      eid = employee.employee_id_pk,
      sen = employee.seniority,
      nam = employee.employee_name,
      pho = employee.phone_number,
      lje = sho == null ? sho.employee_id_fk : null //left outer join with exclusion??
    };

編輯::根據評論中的建議，我嘗試了以下兩種方法。 雖然我不再有語法問題，但以下都沒有返回任何結果，所以這里仍然有問題。

    var emp = from employee in empl
              join jc in jce on callout.job_class_code_fk equals jc.job_class_code_fk
              join av in ab on employee.employee_id_pk equals av.employee_id_fk
              join sh in sho on employee.employee_id_pk equals sh.employee_id_fk into lj
              from rnd2 in lj.DefaultIfEmpty() where sho == null
              orderby employee.seniority descending
              select new
              {
                  eid = employee.employee_id_pk,
                  sen = employee.seniority,
                  nam = employee.employee_name,
                  pho = employee.phone_number,
              };

    var emp = from employee in empl
              join jc in jce on callout.job_class_code_fk equals jc.job_class_code_fk
              join av in ab on employee.employee_id_pk equals av.employee_id_fk
              join sh in sho on employee.employee_id_pk equals sh.employee_id_fk into lj
              from rnd2 in lj.DefaultIfEmpty() where rnd2 == null
              orderby employee.seniority descending
              select new
              {
                  eid = employee.employee_id_pk,
                  sen = employee.seniority,
                  nam = employee.employee_name,
                  pho = employee.phone_number,
              };

Answer 1

好吧（對我而言）最容易閱讀和理解的答案最終成為了這個。

創建兩個列表，我要排除的列表和主列表。

他們我們運行master.Except（排除）和瞧。 我們已經完成了左外連接的效果和排除。

這是工作代碼。 上面的解決方案很可能有效，因為第一個列表的組合方式存在另一個問題。

            var ex = from employee in empl
                 join sh in sho on employee.employee_id_pk equals sh.employee_id_fk
                 select new
                 {
                     eid = employee.employee_id_pk,
                     sen = employee.seniority,
                     nam = employee.employee_name,
                     pho = employee.phone_number,
                 };
        ex.Distinct();

        //get a list of employees who have the enabled orientations and job classifications
        var emp = from employee in empl
                  join jc in jce on employee.employee_id_pk equals jc.employee_id_fk
                  join av in ab on employee.employee_id_pk equals av.employee_id_fk
                  orderby employee.seniority descending
                  select new
                  {
                      eid = employee.employee_id_pk,
                      sen = employee.seniority,
                      nam = employee.employee_name,
                      pho = employee.phone_number,
                  };
        emp = emp.Distinct();
        emp = emp.Except(ex);