关于asp.net操作oracle数据库的问题

SQL code

 
 select c.cod_mitem,b.rot_ord,b.Plan_wkhr_m,(sum(a.plan_wkhr_n) + sum(a.plan_wkhr_o))from web_wlms_o4sequence_user a  
        left join web_wlms_o3sequence b on a.rot_ord_id = b.id 
        left join web_wlms_o2order c on b.num_ord_id = c.id 
        group by c.cod_mitem,b.rot_ord,b.Plan_wkhr_m order by rot_ord 
 

上述代码加载进gridview的时候为什么会出错
Bll代码

C# code

public static DataTable GetAll(){   string sql = "select c.cod_mitem,b.rot_ord,b.Plan_wkhr_m,sum(a.plan_wkhr_n) from web_wlms_o4sequence_user a";   sql = sql + string.Format("left join web_wlms_o3sequence b on a.rot_ord_id = b.id");   sql = sql + string.Format("left join web_wlms_o2order c on b.num_ord_id = c.id");   sql = sql + string.Format("where a.status ='01' group by c.cod_mitem,b.rot_ord,b.Plan_wkhr_m order by rot_ord");   //string sql = "select user_id,user_nm,adr_r from web_user";   DataTable dt = QueryHelper.QueryDataTable(sql);   return dt;}

gridview就是显示不出来
但是换成是注释行代码就没问题
如果执行的是//string sql = "select user_id,user_nm,adr_r from web_user";
那么gridview里面绑定的就是user_id,user_nm,adr_r
问一下，如果执行未注释行代码，gridview里应该绑定对于的是什么~

[解决办法]
绑定的就是你select出来的所有列

还有一点，你在拼接SQL的时候，一定注意空格分割，要不然就会语法错误
应该如下

C# code

string sql = "select c.cod_mitem,b.rot_ord,b.Plan_wkhr_m,sum(a.plan_wkhr_n) from web_wlms_o4sequence_user a ";                sql = sql + string.Format(" left join web_wlms_o3sequence b on a.rot_ord_id = b.id ");                sql = sql + string.Format(" left join web_wlms_o2order c on b.num_ord_id = c.id ");