C#--DataTable的各种操作

1：DataSet转成DataTable

DataSet ds;  //ds已经读取到了数据
DataTable dt1 = ds.Tables[0];  //每次能读取一张表

2：DataTable转成DataSet

DataSet ds = new DataSet(); 
DataTable dt; //dt已经读取到了数据
ds.Tables.Add(dt);

3：datatable中新增一列

DataColumn column5 = new DataColumn();
column5.DataType = Type.GetType("System.String");
column5.ColumnName = "Result1";

DataTable dataTestResult = new DataTable();
dataTestResult.Columns.Add(column5);

4：循环遍历datatable将需要的数据取出存到另外一个datatable中

var count = table2.Rows.Count;

DataRow dx = dataTestResult.NewRow();
for (int i = 0; i < count; i++)
     {
         if (table2.Rows[i][1].ToString().Equals("XXX"))
          {
             DataRow dr = dataOutLook.NewRow();
             dr["XXX"] = table2.Rows[i][2].ToString();
             dr["XXX"]= table2.Rows[i][4].ToString();
             dr["XXX"] = table2.Rows[i][1].ToString();
             dr["XXX"]= table2.Rows[i][3].ToString();
             dataOutLook.Rows.Add(dr);
                   
           }
           if (table2.Rows[i][1].ToString().Equals("XXX"))
           {
              if (table2.Rows[i][2].ToString().Equals("XXX"))
                 {
                    dx["XXX"] = table2.Rows[i][4].ToString();
                 }
                 else if (table2.Rows[i][2].ToString().Equals("XXX"))
                 {
                    dx["XXX"] = table2.Rows[i][4].ToString();
                 }
                 else if (table2.Rows[i][2].ToString().Equals("XXX"))
                 {
                   dx["XXX"] = table2.Rows[i][4].ToString();
                  }
                    
           }
           if (table2.Rows[i][1].ToString().Equals("XXX"))
           {
             if (table2.Rows[i][2].ToString().Equals("XXX"))
             {
               dx["XXX"] = table2.Rows[i][4].ToString();
             }else
             {
                dx["XXX"] = table2.Rows[i][4].ToString();
              }
           }
     }
dataTestResult.Rows.Add(dx);