for (int i = 0; i < dt.Rows.Count; i++)
            {
                string s = "select count(*) from " + dt.Rows[i]["AliasName"] + ".dbo.web_historydata where factoryid=" + dt.Rows[i]["FactoryID"] + " and  datetime >dateadd(HOUR,-1,GetDate())";
                int count = my_SqlHelper.SelectCounts(s);
                
 
if (count<=0)
                {
                    Log.Save("蜀雲泉真帥啊");
                }
            }

　　如果不知道列名是啥子的話，也可以這樣遍歷

   for (int i = 0; i < dataTable.Rows.Count; i++)
            {
                for (int j = 0; j < dataTable.Columns.Count; j++)
                {
                    Console.WriteLine(dataTable.Rows[i][j].ToString()); 
                } 
            }
 

sql查詢結果存入DataTable，然後從DataTable取數據