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ExcelDataReader in C# - How to reference an individual Cell using row and column cordinates

I'm reading an .xlsx spreadsheet into a C# console app with a view to outputting the content as a formatted xml file (to be picked up by another part of the system further down the line).
The problem with the the .xslx file is that it's a pro-forma input document based on, and replacing, an old paper-based order form we used to provide to customers, and the input fields aren't organised as a series of similar rows (except in the lower part of the document which consists of up to 99 rows of order detail lines). Some of the rows in the header part of the form/sheet are a mixture of label text AND data; same with the columns.
Effectively, what I need to do is to be able to cherry pick data from the initial dozen or so rows in order to poke data into the xml structure; the latter part of the document I can process by iterating over the rows for the order detail lines.
I can't use Interop as this will end up as an Azure function - so I've used ExcelDataReader to convert the spreadsheet to a dataset, then convert that dataset to a new dataset entirely composed of string values. But I haven't been able to successfully point to individual cells as I had expected to be using syntax something like
var cellValue = MyDataSet.Cell[10, 2];
I'd be grateful for any advice as to how I might get the result I need.

A Dataset has Tables and those have Rows which hold ColumnValues
A WorkSheet transforms into a Table (with Columns) and the Cells transform to Rows and column values.
To find the cell value at [10,2] on the first Worksheet do:
var cellValue = MyDataSet.Tables[0].Rows[10][2];
Remember that cellValue will be of type object. Cast accordingly.

OleDbConnection only finds cell value when workbook is also open in Excel

I have a program (actually SSIS script task, but I don't suppose that matters) that creates an OLE DB connection to an Excel workbook, and reads the cell values in each worksheet, storing them in a SQL Server table.
Each worksheet has several sections of rows, each section being for a separate product. The first two rows of each product section are a quarter row, and a year row. Here is a screen shot:
I use an OleDbDataReader with a "Select *" command to read the data in each sheet into a DataTable. I have a column called "YearQuarter" in my SQL database, where I store a concatenation of the year row value and the preceding quarter row value, with a hyphen between the two strings:
My code is like this:
OleDbConnection oleExcelConnection = new OleDbConnection(
"Provider=Microsoft.ACE.OLEDB.12.0;" +
"Data Source=" + strWkbkFilePath + ";" +
"Mode=Read;" +
"Extended Properties=\"Excel 8.0;HDR=No;IMEX=1\"");
oleExcelConnection.Open();
DataTable dtCurrSheet = new DataTable();
// Name of table is in strLoadTblNm.
OleDbCommand oleExcelCommand;
OleDbDataReader oleExcelReader;
oleExcelCommand = excel_conn.CreateCommand();
oleExcelCommand.CommandText = "Select * From [" + strLoadTblNm + "]";
oleExcelCommand.CommandType = CommandType.Text;
oleExcelReader = oleExcelCommand.ExecuteReader();
// Load worksheet into data table
dtSheet.Load(oleExcelReader);
oleExcelReader.Close();
Looking at the output data, I noticed that I was getting inconsistent results. Some rows would have a YearQuarter column value that would have only the Year row value in them, while others would have the cell values from both rows. For example, I'd have "2009 - Year End" followed by just "2010", with no " - 1st Qtr." appended to it.
This is because that quarter cell valued is never loaded into the data reader, as the Dataset Visualizer shows:
Notice also that, in the Dataset, the column that is missing the Quarter cell value also has other numeric values missing their formatting (no commas).
If I save the file as a .csv, all cell values are preserved.
However, I noticed that it wasn't consistent. Sometimes I'd run my package and the same row would now have the full value. So, in the above example, I'd get "2010 - 1st Qtr."
I finally realized that it was working as expected only if I happened to have the workbook open in Excel at the same time that the program was running!
Why would this make a difference? Could it be that there is a macro or something in the workbook that is executed by Excel, but not when the workbook is accessed only via an OLE DB connection? Would the fact that it had been executed in Excel then affect the data obtained by OLE DB? If that's the case, how do I get around this? The spreadsheets are provided to me. So I can't modify them.

I think you're having issues with the auto-formatting thing Excel tries to apply. With an OLEDB connection, I can't see how having the sheet open fixes your problem (obviously very strange).
Try Adding IMEX = 1 to your connection options to treat the entire sheet as text to see if this is your issue. Pulled from OLEDB connection does not read data from excel sheet Also another good post from an external site: Tips for reading Excel spreadsheets using ADO.NET
Also, you're pulling data from an excel sheet and writing it to another excel sheet... Same workbook? I have a couple more ideas for ya though depending on your situation.

This bug turns out to be a "feature", and it should come with a big warning sign.
This article (thanks, #vb4all) explains that "ADO.NET scans the first 8 rows of data, and based on that, guesses the datatype for each column. Then it attempts to coerce all data from that column to that datatype, returning NULL whenever the coercion fails!"
In other words, it is treating the worksheet as a relation table, in which all values in a given column are of the same type. Of course, worksheet data is not bound by this restriction.
This behavior can be gotten around by setting IMEX=1 in the connection string options and then modifying these registry settings:
Hkey_Local_Machine/Software/Microsoft/Jet/4.0/Engines/Excel/ImportMixedTypes
Hkey_Local_Machine/Software/Microsoft/Jet/4.0/Engines/Excel/Typ
(Note: registry keys vary depending on 32 vs. 64 bit. E.g., for 64-bit, the first one would be HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Jet\4.0\Engines\Jet 4.0).
I think this was a very risky design, inviting data transfer errors that could easily go unnoticed.

Reading Updatables Excel Columns using C#

I am consuming an Excel spread sheet.
But I would like to know before implement..
If this sheet were updatables...
e.g
Let's suppose that the columns of my spread sheet
changes each second...
Would be a problem to the OleDB?
Should I call the select sql every second to be sure that I have the same values
or there are a better way to do this?
Thank's in advance.

Importing an Excel WorkSheet into a Datatable

I have been asked to create import functionality in my application. I am getting an excel worksheet as input. The worksheet has column headers followed by data. The users want to simply select an xls file from their system, click upload and the tool deletes the table in the database and adds this new data.
I thought the best way would be too bring the data into a datatable object and do a foeach for every row in the datatable insert row by row into the db.
My question is what can anyone give me code to open an excel file, know what line the data starts on in the file, and import the data into a datable object?

Take a look at Koogra.
You instantiate a WorkBook object from a path to an XLS file.
You access a WorkSheet object from the workbook's Sheets property.
You can enumerate over the rows in the worksheet by accessing the sheet's Rows property from index MinRow to MaxRow.
You can enumerate over the cells in a given row by accessing the row's Cells property from index MinColumn to MaxColumn.
Each cell has a Value property (object) as well as a FormattedValue method (string).
Give it a try -- I've found it to be extremely intuitive and easy to use.

You can make use of an OleDbConnection to connect to excel file and the query it using SQL queries.
If it is an Asp.Net application, then you make use of the FileUpload control and get the bytes from the file. Then you will have to manually convert it to a datatable.
Try out these links:
OleDbConnection to excel file
Byte array to datatable

What your looking for is the concept described Here
Providing you dont want to use a third party library anyway, else Dans solution will suit you

First you have to download the dll file namely
NExcel.dll
By using this dll you can make various object which are very useful for
import excel data in .net using both vb as well as c#.
Good luck.

Datatable not returning values from Excel (values from formulas)

A project I am working on requires values from a C# application to update 6 values in an Excel sheet. This excel sheet then populates a named range of items and prices, driven by a number of VLOOKUP formulas and worksheets within the same Excel File.
The two columns in the range are named 'Item' & 'Price'.
'Item' is a column of items concatenated from formulas on a spreadsheet, and these appear fine in the DataTable. However, none of the values in the 'Price' column (all number values from VLOOKUP formulas) appear in the DataTable.
When loading the DataTable in C#, I can see that the two columns' types of string and double are fine. If I replace one of the formula derived values with a hard-coded value the DataTable is fine, so I guess the DataTable itself is working as expected.
If I open the Excel file after the values are passed into it, I can see that the input values went in fine and the formulas have calculated correctly.
So, the only thing I can think is causing the problem is that the formulas are not being recalculated after the values are passed into it.
Is there a way to open an excel file in C# and get it to recalculate all the formulas?

Never mind,
Replaced the OLEDB update with an Excel Interop, opening the Excel file with the Interop allows the formulas to recalculate.