【C#】datatableにシーケンス番号列を追加し、番号を1から順次増やし、第1列に

        /// 

        ///  DataTable       ，   1    
        /// 
        /// DataTable
        /// 
        private DataTable AddSeriNumToDataTable(DataTable dt)
        {        
            //      
            DataTable dtNew;
            if (dt.Columns.IndexOf("  ") >= 0)
            {
                dtNew = dt;
            }
            else //      ,      
            {
                int rowLength = dt.Rows.Count;
                int  colLength= dt.Columns.Count;
                DataRow[] newRows = new DataRow[rowLength];

                dtNew = new DataTable();
                //      “  ” 
                dtNew.Columns.Add("  ");
                for (int i = 0; i < colLength; i++)
                {
                    dtNew.Columns.Add(dt.Columns[i].ColumnName);
                    //  dt    
                    for (int j = 0; j < rowLength; j++)
                    {
                        if (newRows[j] == null)
                            newRows[j] = dtNew.NewRow();
                        //             ，            
                        newRows[j][i+1] = dt.Rows[j][i];
                    }
                }
                foreach (DataRow row in newRows)
                {
                    dtNew.Rows.Add(row);
                }

            }
            //      ， 1  
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                dtNew.Rows[i]["  "] = i + 1;
            }

            return dtNew;           
            
        }