DD.WellWorkover.Cloud/ConsoleApp1/Program.cs

using AsbCloudApp.Data;
using AsbCloudDb.Model;
using AsbCloudInfrastructure.Services;
using AsbCloudInfrastructure.Services.Cache;
using DocumentFormat.OpenXml;
using DocumentFormat.OpenXml.Packaging;
using DocumentFormat.OpenXml.Spreadsheet;
//using AsbSaubReport;
//using AutoMapper;
using Microsoft.EntityFrameworkCore;
using System;
using System.IO;
using System.Linq;

namespace ConsoleApp1
{
    //var options = new DbContextOptionsBuilder<AsbCloudDbContext>()
    //    .UseNpgsql("Host=localhost;Database=postgres;Username=postgres;Password=q;Persist Security Info=True")
    //    .Options;
    //var context = new AsbCloudDbContext(options);

    class Program
    {

        static void Main(/*string[] args*/)
        {

            using var firstExcel = SpreadsheetDocument.Open(@"D:\excels\excel1.xlsx", true);
            using var secondExcel = SpreadsheetDocument.Open(@"D:\excels\excel2.xlsx", true);


            using (var resultExcel = SpreadsheetDocument.Create(@"D:\excels\result.xlsx", SpreadsheetDocumentType.Workbook, true))
            {
                // Add a WorkbookPart to the document.
                var workbookPart = resultExcel.AddWorkbookPart();
                workbookPart.Workbook = new Workbook();

                // Add a WorksheetPart to the WorkbookPart.
                var worksheetPart = workbookPart.AddNewPart<WorksheetPart>();
                worksheetPart.Worksheet = new Worksheet();
                var sheets = workbookPart.Workbook.AppendChild(new Sheets());

                //var sheet = new Sheet() { Id = workbookPart.GetIdOfPart(worksheetPart), SheetId = 1, Name = "Test Sheet" };
                //sheets.Append(sheet);
                workbookPart.Workbook.Save();
            }

            using (var resultExcel = SpreadsheetDocument.Open(@"D:\excels\result.xlsx", true))
            {
                var resultExcelWorkSheetPart = resultExcel.WorkbookPart.WorksheetParts.First();
                var resultExcelSheetData = resultExcelWorkSheetPart.Worksheet.AppendChild(new SheetData());

                foreach (var sheet in firstExcel.WorkbookPart.Workbook.Descendants<Sheet>())
                {
                    var newSheet = new Sheet() { 
                        Id = resultExcel.WorkbookPart.GetIdOfPart(resultExcelWorkSheetPart), 
                        SheetId = sheet.SheetId.Value, 
                        Name = sheet.Name 
                    };
                    resultExcel.WorkbookPart.Workbook.Sheets.Append(newSheet);

                    var firstExcelWorkSheetPart = firstExcel.WorkbookPart.GetPartById(sheet.Id) as WorksheetPart; // get rows from source
                    var firstExcelRows = firstExcelWorkSheetPart.Worksheet.Descendants<Row>(); //  retrieved rows
                    //var firstExcelRows = sheet.Descendants<Row>();

                    foreach (var row in firstExcelRows)
                    {
                        resultExcelSheetData.AppendChild(row.CloneNode(true));
                    }
                }

                //for (uint i = 1; i < 10; i++) // fills cells fine
                //{
                //    var row = new Row();
                //    row.Append(new Cell { CellValue = new CellValue(i.ToString()) });
                //    sheetData.AppendChild(row.CloneNode(true));
                //}
            }


            //resultExcel.Close();
            Console.WriteLine("Done. Press any key to quit.");
            Console.ReadKey();
        }

    }
}