c＃如何使用OleDbCommand在指定的列名称下将指定的值添加到Excel工作表的下一个可用行

Question

Sorry if this has been answered I searched for hours, and I am also brand new to programming.

Currently I have 15 rows with data in my excel spreadsheet, the code below will insert the values into row 40, and pressing the export button again will insert a new row with the values into row 41 etc...

My question is how can I get it to insert a new row with the values directly below my existing data (row 16) and so on with each proceeding export button click. I am looking to keep the command procedure.

 private void exportBtn_Click(object sender, EventArgs e)
{
    OleDbCommand newRow = new OleDbCommand();
    newRow.CommandType = CommandType.Text;
    newRow.CommandText = "INSERT INTO [Sheet1$] ([Company:], [County:], [State:], [Notes:], [User:], [Email:], [Username:], [Password:], [SMMM PWD:], [CAD:]) VALUES (1,2,3,4,5,6,7,8,9,10)";
    newRow.Connection = connectionExl;

    connectionExl.Open();
    newRow.ExecuteNonQuery();
    connectionExl.Close();
}

UPDATE

So far I can get the int of the next available row, Now I want to add values under specified columns to that available row.

For ease let's say I have 2 columns named (column1, column2) and values I want to set respectively are (1,2)

How do I do this?

My code so far:

private void exportBtn_Click(object sender, EventArgs e)
    {
        Excel.Application xlApp = StartExcel();
//Excel.Application xlApp = new Excel.Application();  // instead of above line you can open new instance of Excel application and at the end of procedure xlApp.Application.Quit();
        Excel.Workbook myBook = xlApp.Workbooks.Open(@"C:\Users\path\path\excel.xlsx");

        Excel.Worksheet mySheet = myBook.Sheets[1];
        xlApp.Visible = true; // by default excel is invisible leave it invisible if you just like to add data and save it (also use new instance of Excel in this case) 
        int lastRow = mySheet.Cells.SpecialCells(Excel.XlCellType.xlCellTypeLastCell).Row;
        int openRow = lastRow + 1;
        mySheet.Cells[openRow, 1].Value = "your value for column A";
        mySheet.Cells[openRow, 2].Value = "your value for column B";

        myBook.Save();
        myBook.Close();

    }

    private static Excel.Application StartExcel() // would be better to make it public somewhere in your module
    {
        Excel.Application instance = null;
        try { instance = (Excel.Application)Marshal.GetActiveObject("Excel.Application"); }
        catch (System.Runtime.InteropServices.COMException ex) { instance = new Excel.Application(); }
        return instance;
    }

Answer 1

You would probably need Microsoft.Office.Interop.Excel or other Excel library. Below I put together some sample with Interop you can adjust as needed:

public int getLastRow(Excel.Worksheet ws)
{
    object[,] arData = ws.UsedRange.FormulaR1C1; // FormulaR1C1 returns only string in 2 dimensional array
    for (int iRow = arData.GetUpperBound(0); iRow > 0; iRow--) {
        for (int iCol = 1; iCol <= arData.GetUpperBound(1); iCol++) {
            if (arData[iRow, iCol].ToString() != "") { return iRow; }
        }
    }
    return 0;
}

If your worksheet is not formatted beyond the data range, the below would give you the last row.

int lastRow = ws.Cells.SpecialCells(Excel.XlCellType.xlCellTypeLastCell).Row;

You can start your Excel and adjust as needed to set to your workbook/worksheet:

using System.Runtime.InteropServices;
using Excel = Microsoft.Office.Interop.Excel;

void test()
{
    Excel.Application xlApp = csXL.StartExcel();
    Excel.Worksheet ws = xlApp.ActiveSheet;
    int irow = getLastRow(ws);
}

public static Excel.Application StartExcel()
{
    Excel.Application instance = null;
    try { instance = (Excel.Application)Marshal.GetActiveObject("Excel.Application"); }
    catch (System.Runtime.InteropServices.COMException ex) { instance = new Excel.Application(); }
    return instance;
}

In this case you wouldn't need OleDbCommand you can just insert your data with 2 dimensional array:

object[,] arLoad = new object[0, 9]; arLoad[0, 0] = 1; arLoad[0, 1] = 2;
ws.Range["A" + irow + ":J" + irow].FormulaR1C1 = arLoad; // or use Value instead of FormulaR1C1

Keep in mind when you load data into Excel from 2 dimensional array your array is 0 based, but when you read from Excel your Lower Bound array is 1. I would wait a day maybe someone would post better answer.

Here are few ways to add data under particular column/cell, but it is a lot faster when you are adding data with 2 dimensional array, like I showed above. for small entries speed is not issue.

Excel.Worksheet ws;
Excel.Range rngXL = ws.Cells[3, 2]; // Set range to cell B3
rngXL.Value = "Sample Test"; 
rngXL.FormulaR1C1 = "= 3 + 2";
ws.Cells[4,2].FormulaR1C1 = "5";
ws.Cells[5, 3].Value = "2"; // Cell E3
ws.Range["B5:D5"].Value = "Same text for cells B5,C5,D5";
ws.Range["E5"].Value = "This cell is";

Also read here Unable to open another excel file (when one excel is opened by .net) with simple solution how to make clean Exit with Excel. Where I have edited your code would use open instance of Excel Application. If you just need to update excel and exit it use new instance of Excel and when you done quite the excel application.