Published 4/30/2007 1:45:10 AM  in  General ADO.NET

When copying a row from one datatable to another you might get the error "this row already belongs to another table".

Typically you might write code like this:

            string sConnString = ConfigurationManager.ConnectionStrings["NorthwindConn"].ConnectionString;

            DataSet ds = Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteDataset(
                sConnString,
                CommandType.Text,
                "select * from suppliers order by supplierid");

            int nRowCount = 0;
            DataTable dt = ds.Tables[0];
            DataTable dt2 = dt.Clone();
            dt2.Clear();
            foreach (DataRow row in dt.Rows)
            {
                dt2.Rows.Add(row);
                nRowCount++;
                if (nRowCount == 10)
                {
                    DataRow rowNew = dt2.NewRow();
                    rowNew["supplierid"] = -12345;
                    dt2.Rows.Add(rowNew);
                    nRowCount = 0;
                }
            }

The correct way is instead to "import" the row using ImportRow

            string sConnString = ConfigurationManager.ConnectionStrings["NorthwindConn"].ConnectionString;

            DataSet ds = Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteDataset(
                sConnString,
                CommandType.Text,
                "select * from suppliers order by supplierid");

            int nRowCount = 0;
            DataTable dt = ds.Tables[0];
            DataTable dt2 = dt.Clone();
            dt2.Clear();
            foreach (DataRow row in dt.Rows)
            {
                dt2.ImportRow(row);
                nRowCount++;
                if (nRowCount == 10)
                {
                    DataRow rowNew = dt2.NewRow();
                    rowNew["supplierid"] = -12345;
                    dt2.Rows.Add(rowNew);
                    nRowCount = 0;
                }
            }

It pretty much relates to the an XML error The node to be inserted is from a different document context .