EF中使用SQL语句增删改查

string sqlTaskLimit = $@"UPDATE TaskLimit SET Total = Total + {visit.DeepDose}
        WHERE TaskID = \'{visit.TaskID}\'
        AND(
            ((PeriodType IN(SELECT PeriodType FROM dbo.Period WHERE PeriodStyle = \'R\')) AND \'{visit.EndDT}\' >= PeriodStart)
			OR
            ((PeriodType IN(SELECT PeriodType FROM dbo.Period WHERE PeriodStyle != \'R\')) AND \'{visit.EndDT}\' >= PeriodStart AND \'{visit.EndDT}\' < PeriodExpiry)
			)
        AND Enabled = \'Y\'
        AND ReadingType = 1";
 _db.Database.ExecuteSqlCommand(sqlTaskLimit);
 _db.SaveChanges();

//注：_db是创建的EF上下文对象，ExecuteSQLCommand(string query,params Parameter[] pms);