求大神支招！-----跨节点并行处理的合并问题

//源sql（应用中复杂的sql包含十多张表）

string sql = "Select neflow.id,ne.depart from materialneedflow neflow left outer join materialneed ne on ne.id=neflow.applyid where ne.id=1 and neflow.id=1";

//解析成两条sql，分别去对应的站点执行

string sql11 = "select id,applyid from materialneedflow where id=1";

string sql12 = "select id,depart from materialneed where id=1";



DataSet dataset = new DataSet();

Dictionary<string, string[]> dict = new Dictionary<string, string[]>();

dict.Add("materialneedflow", new string[] { "Data Source=202.193.75.136/ORCL;User ID=site4;Password=123456", sql11 });

dict.Add("materialneed", new string[] { "Data Source=202.193.74.48/ORCL;User ID=site4;Password=123456", sql12 });

//并行地到两个站点去执行，问题1：并行方面能不能修改默认配置呢？

var tables = (from x in dict.AsParallel()

              select Query(x)).ToList();

Dictionary<string, DataTable> dict1 = new Dictionary<string, DataTable>();

for (int i = 0; i < tables.Count; i++)

{

    dict1.Add(tables[i].TableName, tables[i]);

}

//对查出来的两个结果集合并；问题2：这里字段我都转换了类型，但是要写成一个通用模块的话，希望能从Oracle数据库（用的Oracle）中获取类型自动转换c#中类型，该怎么实现啊？？？

var result = from neflow in dict1["materialneedflow"].AsEnumerable()

             join ne in dict1["materialneed"].AsEnumerable()

             on Convert.ToDecimal(IsDBNull(neflow["applyid"])) equals Convert.ToDecimal(ne["id"])

             select new

             {

                 status = Convert.ToDecimal(neflow["id"]),

                 orderdate = Convert.ToDecimal(IsDBNull(ne["depart"]))

             };



static DataTable Query(KeyValuePair<string, string[]> dict)

{

    string host = dict.Value[0];

    string sql = dict.Value[1];

    using (OracleConnection conn = new OracleConnection(host))

    {

        OracleDataAdapter da = new OracleDataAdapter(sql, conn);

        conn.Open();

        DataSet ds = new DataSet();

        da.Fill(ds);

        DataTable table = ds.Tables[0];

        table.TableName = dict.Key;

        return table;

    }

}

public static object IsDBNull(object value)

{

    if (value == DBNull.Value)

    {

        return null;

    }

    else

    {

        return value;

    }

}