將此SQL與左連接轉換爲LINQ

Question

有兩個表格，學校和學期。學校記錄必須顯示，但記錄的詞語可能尚不存在，因此，該詞可能爲空（即左連接）。如果存在，則必須按照當前術語的日期過濾左連接表。這可以在LINQ中完成嗎？

select school.school_name, term.term_start, term.term_end 
from school 
left join term on school.school_id = term.school_id and term.term_start <= '2017-10-21' and term.term_end >= '2017-10-21' 
where school.active = 1 
order by school.school_name 

UPDATE：

一些輸入後，我有一個左連接，但如果一所學校缺少一個學期，我仍然不能使開始和結束日期顯示爲空 - 學校不顯示在所有如果我錯過了一個學期，我想讓學校在第一欄中展示。我在想什麼？這是最新的LinqPad代碼。

var query = ((from sc in Schools.Where(s => s.Active == 1) 
      join t in Terms on sc.School_id equals t.School_id into ts 
      from tsub in ts.DefaultIfEmpty() 
      select new {name = sc.School_name, 
         start = tsub.Term_start, 
         end = tsub.Term_end}) 
      .Where (o => o.start <= DateTime.Now && o.end >= DateTime.Now)) 
      .OrderBy(o => o.name); 

query.Dump(); 

更新＃2

下面是SQL結果的屏幕截圖，我想實現在LINQ同樣的事情：

Answer 1

我終於弄清楚了。如果將.Where（）子句放在連接的表上，如果沒有匹配的記錄，您將獲得空值。這是LinqPad LINQ語句，它可以在.NET MVC中完美運行。

var query = ((from sc in Schools.Where(s => s.Active == 1) 
      join t in Terms.Where(x => x.Term_start <= DateTime.Now && x.Term_end >= DateTime.Now) on sc.School_id equals t.School_id into ts 
      from tsub in ts.DefaultIfEmpty() 
      select new {name = sc.School_name, 
         start = tsub.Term_start, 
         end = tsub.Term_end}) 
      .OrderBy(o => o.name)); 

query.Dump(); 

Answer 2

var query = from sc in school.Where(s = > s.active == 1) 
      join t in term on sc.school_id == t.school_id 
      select new {name = sc.school_name, 
         start = t.term_start, 
         end = term.term_end} 
      .Where (o => o.start <= '2017-10-21' && o.end >= '2017-10-21') 
      .OrderBy(o => o.school_name)