Develop Reference

C# reading an Excel work book, OLEDB or Excel Interop?

I need to read an Excel work book with 2 sheet which have more than 60,000 records. The application is an ASP.Net application so the performance matters.
Which approach should I take? Should I do it using Microsoft.Office.Interop.Excel or should I do it using OLEDB in ADO.Net?
What is the best approach?

Split the book into two worksheet files, convert them to CSV (comma-separated value) form, and process them as text.
I think that would be the best approach perfomance-wise, if you only need to read the data and do not care about formatting, merged cells, formulae etc.

I used always OLEDB in ADO.Net for it.
What the best aproach is, I don't know. But the easiest is like Kaerber says, to read it as 2 .csv files.
Then you can read it like you read a .txt file without 'fancy' libraries.

Use OLEDB for querying (reading) and Interop when modifying Excel.

You can consider using:
gemboxsoftware.com/spreadsheet
or the free alternative:
http://npoi.codeplex.com/

c# read excel worksheet

Could someone help me read a simple excel worksheet in c# app? I'd like to be able to iterate each row and have a handle on each of the columns.
Thanks,
rod.

This one is the easiest method I have found:
Create Excel (.XLS and .XLSX) file from C#

The general method is to use Excel COM Interop. A quick google will find plenty of tutorials. Here's one for creating a sheet - it should point you in the direction (reading is pretty much the same).
An alternative method is to use ADO.Net. This is only really viable if your Excel sheet is well formed as a table ( ie. Database), but is easier than the interop approach.

Here is a sample using OLEDB
http://www.techiesweb.net/2009/12/reading-records-excel-file-insert-database-aspnet/

If you are going to open Excel 2007 or 2010 workbook (ooxml format), you can download Open XML SDK 2.0 for Microsoft Office (which doesn't require you to have MS office installed).

While Excel COM Interop works, it requires Excel to be installed on the client machine. If that isn't an issue then all good, but if it is you might consider looking at the Aspose.Cells library (no affiliation, just used them before). They're simple and powerful, although do carry a commercial license cost.

I've used ADO.NET and Jet in the past. Be warned that if you have columns that aren't obviously of one type you will see weird things happen. Jet tries to assign a datatype to a column based on the first several vales. The nice thing is that you can query the spreadsheet like it is a table.

Reading and parsing Excel files in C#

What is the best way/library to read Excel 2003 and 2007 files using C#? I need to do some heavy parsing.

Do you need to parse the file, or deal with the contents?
For parsing the file, you'd better hope it's in Open Office XML format, because the previous binary version is not documented at all.
If you just need to deal with the contents, use the Office Interop libraries.

You can try SmartXLS for .Net,it support most features of excel(cell formatting,Charts,formulas,pivot tables etc),and can read/write both the excel97-2003 xls format and the excel2007 openxml format.

I would start by trying to use ADO.NET.
If that doesn't work, I used xlsio by Syncfusion.

If the data is in some kind of table format I'd suggest to try using OleDbConnection and treating the Excel sheet as another data connection. Otherwise Interop is ok if it's not on a server or anything like that.

You can use the MS Office interop assemblies (see here) to access Excel files from .NET applications.

There are a number of 3rd party tools you can use. I would avoid using the Interop libraries as they can be pretty slow. I have used Aspose.Cells before and it works pretty well. It does cost some money though.

How can I programmatically create, read, write an excel without having office installed?

I'm confused as hell with all the bazillion ways to read/write/create excel files. VSTO, OLEDB, etc, but they all seem to have the requirement that office must be installed.
Here is my situation: I need to develop an app which will take an excel file as input, do some calculations and create a new excel file which will basically be a modification of the first excel file. All with the constraint that the machine that runs this may not have office installed. (Don't ask why...)
I need to support all excel formats. The only saving grace is that the formats spreadsheets themselves are really simple. Just a bunch of columns and values, nothing fancy. And unfortunately no CSV as the end user might not even know what a CSV file is.

write your excel in HTML table format:
<html>
<body>
<table>
<tr>
<td style="background-color:#acc3ff">Cell1</td>
<td style="font-weight:bold">Cell2</td>
</tr>
</table>
</body>
</html>
and give your file an xls extension. Excel will convert it automatically

Without Office installed you'll need something designed to understand the Excel binary file format (unless you only want to open Office 2007 .xlsx files).
The best I've found (and that I use) is SpreadsheetGear, which in addition to being .NET native, is much faster and more stable then the COM/OLE solutions (which I've used in the past)

read and write csv files instead. Excel reads them just fine and they're easier to use. If you need to work against .xls files then try having support for OpenOffice as well as Excel. OpenOffice can read and write excel files.

Did you consider way number bazillion and one: using the Open XML SDK? You can retain styles and tweak it to your liking. Anything you can do in an actual file is possible to achieve programatically. The SDK comes with a tool called Document Reflector that shows the underlying XML and even shows LINQ statements that can be used to generate them. That is key to playing around with it, seeing how the changes are made, then recreating that in code.
The only caveat is this will work for the new XML based formats (*.xlsx) not the older versions. There's a slight learning curve but more material is making its way on blogs and other sites.

If cost is not an issue, I'd suggest looking in Aspose's Excel product. I use their Word product and I've been satisfied.
Aspose.Cells

Excel XLSX files "just" XML files - more precisely ZIP files containing several XML files. Just rename a Excel file Test.xslx to Test.zip and open it with your favourit ZIP program. XML schemas are, afaik, standardized and availiable. But I think it might not be that easy to manipulate them only using primitive XML processiing tools and frameworks.

Excel files are in a proprietary format so (afaik) you're not going to be able to do this without having the office interop available. Some third party tools exist (which presumably licence the format from MS?) but I've not used them myself to comment on their usefulness.
I assume that you can't control the base file format, i.e. simple CSV or XML formats aren't going to be possible?

I used to use a very nice library called CarlosAg, which uses Excel XML format. It was great (and Excel recognizes the format), and also incredibly fast. Check it out here.
Oh, as a side note, we used to use this for the very same reason you need it. The servers that generated these files were not able to have Excel installed.

If you cannot work with CSV files as per #RHicke's suggestion, and assuming you are working on a web app, since a desktop app would be guaranteed to have XL installed as per requirements.
I'd say, create your processing app as a webservice, and build an XL addin which will interact with your webservice directly from XL.

For XLSX files, look at using http://www.codeplex.com/ExcelPackage. Otherwise, some paid 3rd party solutions are out there, like the one David suggested.

I can understand the requirement of not having office installed on a server machine.
There are many libraries like aspose being available, some of them requiring license though.
If you are targeting MS Excel formats, then a native, Interoperability library, ACE OLEDB data provider, from Microsoft is available which you can install on a machine and start reading, writing programmatically. You need to define a connection string and commands as per you needs. (Ref: This article #yoursandmyideas)talks about using this library along with setup and troubleshooting information.

Reading and writing XLS files

Im searching for a .Net component to read and write xls files from an application in working on. I dont want use automation with Excel.
It should support reading and write Excel 97 and newer versions. And it would be great if its open source or free since its a very low budget project.
I have found this one: MyXLS that looks very promising.
Do you know of any alternatives?

SpreadsheetGear for .NET reads and writes CSV / XLS / XLSX and does more.
You can see live ASP.NET samples with C# and VB source code here and download a free trial here.
Disclaimer: I own SpreadsheetGear LLC

As an alternative I can suggest Excel
Jetcell .NET component. It pretty
Excel component. It does not use Jet
drivers and excel automation. All
information please find at:
http://www.devtriogroup.com/ExcelJetcell

You can use EasyXLS. The component reads xls files from Excel 97 and xlsx/xlsb files from Excel 2007-2010.
www.easyxls.com
You can find samples for how to use on their website.

This must be one of the most asked questions on SO.

First - which version of Excel must you support? For example, xslx (2007) is just a zip file with xml files inside - so you should be able to use #ZipLib and xml generation / copying.
Another option is to write CSV and let the user import it - obviously more appropriate for data than for calculations.
There is also the 2003 xml-spreadsheet format - with contents like:
<Table ss:ExpandedColumnCount="3" ss:ExpandedRowCount="1" x:FullColumns="1"
x:FullRows="1" ss:DefaultRowHeight="15">
<Row>
<Cell><Data ss:Type="Number">1</Data></Cell>
<Cell><Data ss:Type="Number">2</Data></Cell>
<Cell ss:Formula="=RC[-2]+RC[-1]"><Data ss:Type="Number">3</Data></Cell>
</Row>
</Table>
Pretty easy to create by hand...

Where I work they have this one: http://www.syncfusion.com/products/xlsio/backoffice/default.aspx
Have used it a couple of times and it is pretty easy to use.

I've worked with aspose for a long time and can really recommend it.
http://www.aspose.com/categories/file-format-components/aspose.cells-for-.net-and-java/default.aspx
Commercial product
Great support
Excel 97-2007
100% native .net