export Excel to DataTable using NPOI

Question

I want to read Excel Tables 2010 xlsx using NPOI and then export data to DataTables but don\'t know how to use it. Can anyone show me step by step how to export Excel to Datatab

Answer 1

NPOI is a great and free way to read Excel files, and now in version 2 you can read both XLS and XLSX file types.

1. Get the latest version of NPOI at their website: https://npoi.codeplex.com/
2. In your project add references to the following files: NPOI.dll, NPOI.OOXML.dll and NPOI.OpenXml4Net.dll.
3. Add the following Usings: using NPOI.SS.UserModel; using NPOI.HSSF.UserModel; using NPOI.XSSF.UserModel;

Now the following code does the trick, comments are in spanish, sorry for that :-p

private DataTable Excel_To_DataTable(string pRutaArchivo, int pHojaIndex)
    {
        // --------------------------------- //
        /* REFERENCIAS:
         * NPOI.dll
         * NPOI.OOXML.dll
         * NPOI.OpenXml4Net.dll */
        // --------------------------------- //
        /* USING:
         * using NPOI.SS.UserModel;
         * using NPOI.HSSF.UserModel;
         * using NPOI.XSSF.UserModel; */
        // --------------------------------- //
        DataTable Tabla = null;
        try
        {
            if (System.IO.File.Exists(pRutaArchivo))
            {

                IWorkbook workbook = null;  //IWorkbook determina se es xls o xlsx              
                ISheet worksheet = null;
                string first_sheet_name = "";

                using (FileStream FS = new FileStream(pRutaArchivo, FileMode.Open, FileAccess.Read))
                {
                    workbook = WorkbookFactory.Create(FS); //Abre tanto XLS como XLSX
                    worksheet = workbook.GetSheetAt(pHojaIndex); //Obtener Hoja por indice
                    first_sheet_name = worksheet.SheetName;  //Obtener el nombre de la Hoja

                    Tabla = new DataTable(first_sheet_name);
                    Tabla.Rows.Clear();
                    Tabla.Columns.Clear();

                    // Leer Fila por fila desde la primera
                    for (int rowIndex = 0; rowIndex <= worksheet.LastRowNum; rowIndex++)
                    {
                        DataRow NewReg = null;
                        IRow row = worksheet.GetRow(rowIndex);
                        IRow row2 = null;

                        if (row != null) //null is when the row only contains empty cells 
                        {
                            if (rowIndex > 0) NewReg = Tabla.NewRow();

                            //Leer cada Columna de la fila
                            foreach (ICell cell in row.Cells)
                            {
                                object valorCell = null;
                                string cellType = "";

                                if (rowIndex == 0) //Asumo que la primera fila contiene los titlos:
                                {
                                    row2 = worksheet.GetRow(rowIndex + 1); //Si es la rimera fila, obtengo tambien la segunda para saber los tipos:
                                    ICell cell2 = row2.GetCell(cell.ColumnIndex);
                                    switch (cell2.CellType)
                                    {
                                        case CellType.Boolean: cellType = "System.Boolean"; break;
                                        case CellType.String: cellType = "System.String"; break;
                                        case CellType.Numeric:
                                            if (HSSFDateUtil.IsCellDateFormatted(cell2)) { cellType = "System.DateTime"; }
                                            else { cellType = "System.Double"; }        break;
                                        case CellType.Formula:
                                            switch (cell2.CachedFormulaResultType)
                                            {
                                                case CellType.Boolean: cellType = "System.Boolean"; break;
                                                case CellType.String: cellType = "System.String"; break;
                                                case CellType.Numeric:
                                                    if (HSSFDateUtil.IsCellDateFormatted(cell2)) { cellType = "System.DateTime"; }
                                                    else { cellType = "System.Double"; }    break;
                                            }
                                            break;
                                        default:
                                            cellType = "System.String"; break;
                                    }

                                    //Agregar los campos de la tabla:
                                    DataColumn codigo = new DataColumn(cell.StringCellValue, System.Type.GetType(cellType));
                                    Tabla.Columns.Add(codigo);
                                }
                                else
                                {
                                    //Las demas filas son registros:
                                    switch (cell.CellType)
                                    {
                                        case CellType.Blank:    valorCell = DBNull.Value; break;
                                        case CellType.Boolean:  valorCell = cell.BooleanCellValue; break;
                                        case CellType.String:   valorCell = cell.StringCellValue; break;
                                        case CellType.Numeric:
                                            if (HSSFDateUtil.IsCellDateFormatted(cell)) { valorCell = cell.DateCellValue; }
                                            else { valorCell = cell.NumericCellValue; } break;
                                        case CellType.Formula:
                                            switch (cell.CachedFormulaResultType)
                                            {
                                                case CellType.Blank:    valorCell = DBNull.Value; break;
                                                case CellType.String:   valorCell = cell.StringCellValue; break;
                                                case CellType.Boolean:  valorCell = cell.BooleanCellValue; break;
                                                case CellType.Numeric:
                                                    if (HSSFDateUtil.IsCellDateFormatted(cell)) { valorCell = cell.DateCellValue; }
                                                    else { valorCell = cell.NumericCellValue; }
                                                    break;
                                            }
                                            break;                                          
                                        default: valorCell = cell.StringCellValue; break;
                                    }
                                    NewReg[cell.ColumnIndex] = valorCell;
                                }
                            }
                        }
                        if (rowIndex > 0) Tabla.Rows.Add(NewReg);
                    }
                    Tabla.AcceptChanges();
                }
            }
            else
            {
                throw new Exception("ERROR 404: El archivo especificado NO existe.");
            }
        }
        catch (Exception ex)
        {
            throw ex;
        }
        return Tabla;
    }

The above code assumes the first row of the sheet has the column names. The code also determines the data Type of each cell and tries to convert it to an ADO data type. Blank cells are converted to null.

Hope this helps you and others in the same situation.