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How to copy MS Excel Worksheet into datatable in C#

I have a Excel Sheet that i need to copy into Data table and later insert into Mysql Database table.I am trying to use Microsoft.Office.Interop.Excel.here is the codes that i have tried.
Workbook workbook = new Workbook();
Microsoft.Office.Interop.Excel.DataTable dataTable = sheet.ExportDataTable();
But i dont know how to import sheet from the directory.I am trying these things in Windows Form Application.
Please help me.

Assuming you're trying to open an existing Excel file from the file system, here's a link to a CodeProject article on how to manipulate Excel files using C#. This snippet of code is right on the article's page showing how to open an existing Excel spreadsheet:
string workbookPath = "c:/SomeWorkBook.xls";
Excel.Workbook excelWorkbook = excelApp.Workbooks.Open(workbookPath,
0, false, 5, "", "", false, Excel.XlPlatform.xlWindows, "",
true, false, 0, true, false, false);
As you can see, you have to use the Application object's Workbooks property to open the Workbook and add it to the Workbooks collection.

Take a look at Workbook.Sheets[0] (each of those links to the msdn reference). I don't see a direct way to pull that into a DataTable, but you could iterate through the Rows(of class Range) member and simply add to your DataTable that way. From a DataTable it would then be trivial to generate a query using any of the MySQL libraries.

Open Copy of Excel Based on Template

I have a WinForms app written in C# that uses the following code to open an Excel Template, prior to exporting data from a SQL database into the Worksheets of the Template.
Microsoft.Office.Interop.Excel.Application oXL = new Microsoft.Office.Interop.Excel.Application();
oXL.Visible = true;
oXL.DisplayAlerts = false;
Microsoft.Office.Interop.Excel.Workbook mWorkBook = oXL.Workbooks.Open(path, 0, false, 5, "", "", false, Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "", true, false, 0, true, false, false);
Excel.Worksheet mWorkSheet = mWorkBook.Worksheets["Invoice"];
However, this code actually opens the Template itself, so that any data exported from SQL into the workbook, is saved to the Template. What I want is to programmatically open a copy of the template in the same way this works when you double click a template directly in Windows Explorer and a copy is automatically created, without the original Template being touched.
How can I do this programmatically?

You can actually use the Workbooks.Add function of your Excel Application object, and pass in the template path as a parameter. Any future changes that you do programmatically will be done to an as-yet-to-be-saved copy in memory.
I've found that this is useful when you want to prepare / preformat a new excel workbook for a user to interact with later.
string templatePath = "c:\\temp\\template.xlsx";
Workbook wb = oXL.Workbooks.Add(templatePath);
//wb will be a memory copy of template.xlsx

then copy the file you want to open to the destination of your choice and open the copy...
System.IO.File.Copy(sourceFile, destFile, true);
the sourcefile is the original file;
the destFile is your copy
and you open the destfile with oXL.Workbooks.Opeen("path to destfile",....)
So your original file is never touched:)

How to insert values to excel cells using a Windows Service C#

Im trying to pass 8 string values in to a row in an already existing excel spreadsheet and then be able to select that row programmatically using C#. I am using a Windows Service with a file system watcher that is constantly monitoring a directory for a file to be added once the file is added it needs to extract the file contents in to object properties and then write them to an excel sheet. Would anyone have any idea how to do this without having to pay for any additional excel extensions? I am using excel 2007 and Visual Studio 2012. Any help would be much appreciated.
Thanks
Bernard

Hi I actually got it working there. I used the following code to write to a specific cell in an already existing excel sheet:
string path = #"C:\ProjectTesting\TwsDde.xlsm";
oXL = new Microsoft.Office.Interop.Excel.Application();
oXL.Visible = true;
oXL.DisplayAlerts = false;
mWorkBook = oXL.Workbooks.Open(path, 0, false, 5, "", "", false, Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "", true, false, 0, true, false, false);
//Get all the sheets in the workbook
mWorkSheets = mWorkBook.Worksheets;
//Get the allready exists sheet
mWSheet1 = (Microsoft.Office.Interop.Excel.Worksheet)mWorkSheets.get_Item("Basic Orders");
Microsoft.Office.Interop.Excel.Range range= mWSheet1.UsedRange;
mWSheet1.Cells[12, 1] = "bla bla bla";
This code was taken from this article which also goes on to save the excel sheet:
http://rmanimaran.wordpress.com/2011/02/15/programmatically-insert-to-existing-excel-file-using-c/
I hope this helps somebody else.
Thanks
Bernard

Saving Excel Spreadsheet using Interop C#

static void Main()
{
Application excelapp = new Application();
Workbook book = excelapp.Workbooks.Open(#"C:\HWYFAB.xlsx",
0, false, 5, "", "", false, XlPlatform.xlWindows , "",
true, false, 0, true, false, false);
Worksheet sheet = (Worksheet)book.Sheets[1];
Range cell = (Range)sheet.Cells[3, 2];
Console.WriteLine(cell.Text);
cell.ClearContents();
book.Close(true, "HWYFAB.xlsx", false);
excelapp.Quit();
}
This program runs and exits as expected. It does print the correct value that's in cell B3 to the console. When closing it asks if I want to replace the existing file. I click yes. When I open the spreadsheet in Excel, the value is still in cell B3 despite the cell.ClearContents().
Any thoughts?

Your call to cell.ClearContents() will clear formulas and value constants from the cell. This should absolutely be working. You can confirm this after your call to cell.ClearContents() by testing if cell.Value2 == null, which should be true.
I believe that the problem with your code is in the call to book.Close(true, "HWYFAB.xlsx", false). The problem is that you are explicitly passing in the name of your workbook, but you are leaving off the path. (Note that when you open the workbook you are including the full path, including the "C:\" directory.) By leaving off the full path to the workbook when you save, you are saving to the current directory, which could be "My Documents" or anywhere else.
If you wish to save the workbook in-place, at its original location, then you should pass in Type.Missing for the Filename parameter. For example:
book.Close(true, Type.Missing, false);
This idea is untested, but I'm fairly confident that this should work for you. Give it a try...
-- Mike

Problem in opening Excel files externally during execution of a C# application

I have created a C# application whose inputs are some large Excel files.
In my code, I open it, process and then close it. The whole process takes some 15-20 minutes. During this time when I try to open some other Excel files(1) externally, anyone of the input Excel files(2) (which is currently being processed) is also getting opened along with this. When I try to close this(2), exception occurs and the tool aborts its process.
I think the problem occurs because the Excel files are opened under the same instance. How can I avoid this?

SpreadsheetGear for .NET will open only the workbooks you want it to open and in most cases runs much faster than using the Excel COM Interop APIs from .NET.
You can see samples here and download a free trial here if you want to try it yourself.
Disclaimer: I own SpreadsheetGear LLC

The following is the code:
Excel.ApplicationClass objExcelApp = new Excel.ApplicationClass();
Excel.Workbook objWorkbook = objExcelApp.Workbooks.Open("File Name",0, true, 1, "", "", true, Excel.XlPlatform.xlWindows,Type.Missing, false, false, 0,true);
Excel.Worksheet objWorksheet = (Excel.Worksheet) objWorkbook.Worksheets.get_Item(1);
Excel.Range objRangeData =objWorksheet.UsedRange;
// Some proces
GC.Collect();
objRangeData.Clear ();
objWorkbook.Close(false, strDictFile, false);
objExcelApp.Workbooks.Close();
objExcelApp.Quit();
System.Runtime.InteropServices.Marshal.ReleaseComObject(objRangeData);
System.Runtime.InteropServices.Marshal.ReleaseComObject(objWorksheet);
System.Runtime.InteropServices.Marshal.ReleaseComObject(objWorkbook); System.Runtime.InteropServices.Marshal.ReleaseComObject(objExcelApp);
objWorksheet = null;
objWorkbook = null;
objExcelApp = null;
GC.Collect();
GC.WaitForPendingFinalizers();