行がすでに別のテーブルに属しているという問題に対する C# ソリューションの詳細な紹介

DataTable dtContract_src = Oper.GetDataTable("select * from T_Contract where ProjectID=" + ProjectID_src + " and Flag=0", con_src);
                            foreach (DataRow dr in dtContract_src.Rows)
                            {
                                String ContractID_src = dr["ContractID"].ToString();
                                DataTable dtContract_dst = Oper.GetDataTable("select * from T_Contract where ProjectID=" + ProjectID_src + "
                                 and ContractID=" + ContractID_src + " and Flag=0", con_dst);
                                if (dtContract_dst.Rows.Count != 0)
                                {
                                    impContract_exist++;
                                    continue;
                                }

                                dtContract_dst.Rows.Add(dr);

                                String columns = "";
                                String paramss = "";
                                OleDbCommand updateCmd = con_dst.CreateCommand();
                                foreach (DataColumn dc in dtContract_dst.Columns)
                                {
                                    if (columns == "")
                                    {
                                        columns = dc.ColumnName;
                                        paramss = "@" + dc.ColumnName;
                                    }
                                    else
                                    {
                                        columns += ", " + dc.ColumnName;
                                        paramss += ", @" + dc.ColumnName;
                                    }
                                    updateCmd.Parameters.Add(new OleDbParameter(dc.ColumnName, dc.DataType);
                                }
                                updateCmd.CommandText = "insert into T_Contract(" + columns + ") Values(" + paramss + ")";

                                updateCmd.ExecuteNonQuery();

                                //OleDbDataAdapter dataAdap = new OleDbDataAdapter();
                                //dataAdap.InsertCommand = updateCmd;
                                //dataAdap.Update(dtContract_dst);

                            }

dtContract_dst.Rows.Add(dr);

dtContract_dst.Rows.Add(dr.ItemArray);