var result = from lr in _db.LeaveRequest
join th in _db.TotalHourslu
on lr.TotalHoursEffect
equals th.Minutesselect
select new { lr.TotalHoursEffect, th.Minutes, tr.Display };
错误:当前上下文中不存在名称“_db”当前上下文中不存在名称“_db”当前上下文中不存在名称“tr”