LINQ相當於此查詢

Question

SELECT StudentHistoryId, StudentId, Grade, CreatedAt, ModifiedAt, ModifiedBy, Active 
FROM TABLENAME TN 
    INNER JOIN (SELECT StudentId, MAX(ModifiedAt) AS ModifiedAt FROM TABLENAME GROUP BY StudentId) M 
      ON TN.StudentId = M.StudentId AND TN.ModifiedAt = M.ModifiedAt 

Answer 1

這裏是一個直接translaton：

var subquery = from tn in dc.TABLENAME 
       group tn by tn.StudentId into g 
       select new { StudentId = g.Key, ModifiedAt = g.Max(x => x.ModifiedAt) }; 
var query = from tn in dc.TABLENAME 
      join m in subquery 
       on new { tn.StudentId, tn.ModifiedAt } 
       equals new { m.StudentId, m.ModifiedAt } 
      select new 
      { 
       tn.StudentHistoryId, 
       tn.StudentId, 
       tn.Grade, 
       tn.CreatedAt, 
       tn.ModifiedAt, 
       tn.ModifiedBy, 
       tn.Active 
      };