Export / import data

Microsoft Office 2010: Primary Interop Assemblies Redistributable

http://www.microsoft.com/en-us/download/details.aspx?id=3508

send data to Excel

        strInsert.Append("Insert Into [" + NewXLSheetName + xlSheetIndex.ToString() + 
                         "$](" + SqlInsert.ToString() + ") Values (");
        foreach (DataColumn dCol in DTable.Columns)
        {
            if (dCol.DataType.ToString().ToLower().Contains("int"))
            {
                if (DTable.Rows[count][dCol.Ordinal].ToString() == "")
                    strInsert.Append("NULL");
                else
                    strInsert.Append(DTable.Rows[count][dCol.Ordinal]);

Get data from Excel

        OleDbDataAdapter xlDA = new OleDbDataAdapter("Select" + AdditionalFields + 
                                " * from [" + xlSheetName + "$] ", xlConn);
        xlDA.Fill(xlTDS);

http://www.codeproject.com/Articles/33271/Import-and-Export-to-Multiple-Worksheets