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Why does OleDbDataAdapter leave artifacts when filling a DataTable?

I wrote some methods which are supposed to fetch a DataTable for each WorkSheet in a Excel file:
Step 1 is to get the names of all sheets included in a .xlsx file:
private static List<string> GetSheetNames(string filePath)
{
List<string> sheetNames = new List<string>();
DataTable dt = null;
try
{
OleDbConnection connection = new OleDbConnection("provider=Microsoft.ACE.OLEDB.12.0;Data Source='" + filePath + "';Extended Properties='Excel 12.0 Xml;HDR=YES;'");
connection.Open();
dt = connection.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
if (dt == null)
{
return null;
}
// Add the sheet name to the string array.
foreach (DataRow row in dt.Rows)
{
sheetNames.Add(row["TABLE_NAME"].ToString());
}
}catch(Exception ex)
{
MessageBox.Show(ex.Message);
}
return sheetNames;
}
Step 2 is to read every sheet and return an according DataTable:
private static DataTable ReadExcelSheet(string filePath,string sheetName)
{
DataTable table = new DataTable();
ValidateSheetName(ref sheetName);
try
{
OleDbConnection connection;
DataSet DtSet;
OleDbDataAdapter cmd;
connection = new OleDbConnection("provider=Microsoft.ACE.OLEDB.12.0;Data Source='" + filePath + "';Extended Properties='Excel 12.0 Xml;HDR=YES;'");
cmd = new OleDbDataAdapter("select * from ["+sheetName+"]", connection);
cmd.TableMappings.Add("Table", sheetName.Replace("$",string.Empty));
DtSet = new DataSet();
cmd.Fill(DtSet);
table = DtSet.Tables[0];
connection.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
return table;
}
Both methods are called from this last method which returns a List<DataTable>:
private static List<DataTable> ConvertExcelToTables(string filePath)
{
List<string> sheetNames = GetSheetNames(filePath);
List<DataTable> tableList = new List<DataTable>();
foreach(string sheetName in sheetNames)
{
tableList.Add(ReadExcelSheet(filePath,sheetName));
}
return tableList;
}
There is also a little helper method which should be irrelevant for the question:
private static void ValidateSheetName(ref string sheetName)
{
sheetName = sheetName.EndsWith("$") ? sheetName : sheetName + "$";
}
If I take one sheet from a example file it looks like this:
Now no matter if I just look into the DataTable while debugging or if I bind it as a DataSource of a DataGridView the result looks a little weird:
My guess is that this might have to do with Excel sheets beginning counting with 1 not with 0. But even if this is the case I can't really think of a solution. Or did I miss something. Actually this is a pity because this seems to be a clean solution imo.

No, the problem is caused by
HDR=YES;
in your connection string.
Change it to
HDR=NO;
HDR=YES means that the first line of your Excel sheets is assumed to contain the fields' names of your table. But this is not the case with the sheet shown as an example. Indeed the OleDb provider cannot determine the name of the second column (it's blank) and thus it assigns the default value (the letter F followed by the progressive number of the column)
You could find a lot of examples and explanations about connectionstrings for excel at connectionstrings.com

How to read excel (.xlsm) file, that file is using finansu add-in through C#

I have a excel (.xlsm) file with stock markets live data update through the excel add-in "finansu".
When I try to read excel data through the C# application in stock name column it shows the proper stock name but at the value column it does not show any thing. That stock value column is updated live values through the finansu add-in.
Please help me out to read these values as well.
Thanks in advance.
Below is the source code:
connString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + fileName + ";Extended Properties=\"Excel 12.0;HDR=Yes;IMEX=1\";";
query = "SELECT * FROM [RealTime$]";
conn = new OleDbConnection(connString);
if (conn.State == ConnectionState.Closed)
conn.Open();
cmd = new OleDbCommand(query, conn);
da = new OleDbDataAdapter(cmd);
dt = new System.Data.DataTable();
da.Fill(dt);

OLEDB won't be able to retrieve the data you want. I'm not familiar with the finansu add-in, but Excel Interop should be able to get what you need.
Microsoft.Office.Interop.Excel
Sample code:
using Microsoft.Office.Interop.Excel;
using System;
namespace ConsoleApplication4
{
class Program
{
static void Main(string[] args)
{
var filename = #"C:\temp\Book1.xlsx";
var excel = new Microsoft.Office.Interop.Excel.Application();
var wb = excel.Workbooks.Open(filename);
Worksheet realtime = wb.Sheets["RealTime"];
foreach (Range row in realtime.UsedRange.Rows)
{
Console.WriteLine("{0}", row.Cells[1, 1].Value); // Column A
Console.WriteLine("{0}", row.Cells[1, 2].Value); // Column B
// etc ...
}
wb.Close(SaveChanges: false);
}
}
}

How can I read the rows of an Excel csv or xls file into an ASP.NET app from a remote location using C#?

Here's my situation. I'm designing a program that takes Excel files (which may be in csv, xls, or xlsx format) from a remote network drive, processes the data, then outputs and stores the results of that process. The program provides a listbox of filenames that are obtained from the remote network drive folder using the method detailed in the accepted answer here. Once the user selects a filename from the listbox, I want the program to find the file and obtain the information from it to do the data processing. I have tried using this method to read the data from the Excel file while in a threaded security context, but that method just fails without giving any kind of error. It seems to not terminate. Am I going about this the wrong way?
Edit - (Final Notes: I have taken out the OleDbDataAdapter and replaced it with EPPlus handling.)
I was able to scrub sensitive data from the code, so here it is:
protected void GetFile(object principalObj)
{
if (principalObj == null)
{
throw new ArgumentNullException("principalObj");
}
IPrincipal principal = (IPrincipal)principalObj;
Thread.CurrentPrincipal = principal;
WindowsIdentity identity = principal.Identity as WindowsIdentity;
WindowsImpersonationContext impersonationContext = null;
if (identity != null)
{
impersonationContext = identity.Impersonate();
}
try
{
string fileName = string.Format("{0}\\" + Files.SelectedValue, #"RemoteDirectoryHere");
string connectionString = string.Format("Provider=Microsoft.ACE.OLEDB.14.0; data source={0}; Extended Properties=Excel 14.0;", fileName);
OleDbDataAdapter adapter = new OleDbDataAdapter("SELECT * FROM Sheet1", connectionString);
DataSet ds = new DataSet();
adapter.Fill(ds, "Sheet1");
dataTable = ds.Tables["Sheet1"];
}
finally
{
if (impersonationContext != null)
{
impersonationContext.Undo();
}
}
}
Additional Edit
Now xlsx files have been added to the mix.
Third Party
Third party solutions are not acceptable in this case (unless they allow unrestricted commercial use).
Attempts - (Final Notes: Ultimately I had to abandon OleDb connections.)
I have tried all of the different connection strings offered, and I have tried them with just one file type at a time. None of the connection strings worked with any of the file types.
Permissions
The User does have access to the file and its directory.

Your connection string might be the issue here. As far as I know, there isn't 1 that can read all xls, csv, and xlsx. I think you're using the XLSX connection string.
When I read xls, i use the following connection string:
#"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + sFilePath + ";Extended Properties='Excel 8.0;HDR=YES;IMEX=1;'"
Having said that, I recommend using a 3rd party file reader/parser to read XLS and CSV since, from my experience, OleDbDataAdapter is wonky depending on the types of data that's being read (and how mixed they are within each column).
For XLS, try NPOI https://code.google.com/p/npoi/
For CSV, try http://www.codeproject.com/Articles/9258/A-Fast-CSV-Reader
For XLSX, try EPPlus http://epplus.codeplex.com/
I've had great success with the above libraries.

Is it really important that you use an OleDb interface for this? I've always done it with Microsoft.Office.Excel.Interop, to wit:
using System;
using Microsoft.Office.Interop.Excel;
namespace StackOverflowExample
{
class Program
{
static void Main(string[] args)
{
var app = new Application();
var wkbk = app.Workbooks.Open(#"c:\data\foo.xls") as Workbook;
var wksht = wkbk.Sheets[1] as Worksheet; // not zero-based!
for (int row = 1; row <= 100; row++) // not zero-based!
{
Console.WriteLine("This is row #" + row.ToString());
for (int col = 1; col <= 100; col++)
{
Console.WriteLine("This is col #" + col.ToString());
var cell = wksht.Cells[row][col] as Range;
if (cell != null)
{
object val = cell.Value;
if (val != null)
{
Console.WriteLine("The value of the cell is " + val.ToString());
}
}
}
}
}
}
}

As you will be dealing with xlsx extension, you should rather opt for the new connection string.
public static string getConnectionString(string fileName, bool HDRValue, bool WriteExcel)
{
string hdrValue = HDRValue ? "YES" : "NO";
string writeExcel = WriteExcel ? string.Empty : "IMEX=1";
return "Provider=Microsoft.ACE.OLEDB.12.0;" + "Data Source=" + fileName + ";" + "Extended Properties=\"Excel 12.0 xml;HDR=" + hdrValue + ";" + writeExcel + "\"";
}
Above is the code for getting the connection string. First argument expects the actual path for file location. Second argument will decide whether to consider first row values as column headers or not. Third argument helps decide whether you want to open the connection to create and write the data or simply read the data. To read the data set it to "FALSE"
public static ReadData(string filePath, string sheetName, List<string> fieldsToRead, int startPoint, int endPoint)
{
DataTable dt = new DataTable();
try
{
string ConnectionString = ProcessFile.getConnectionString(filePath, false, false);
using (OleDbConnection cn = new OleDbConnection(ConnectionString))
{
cn.Open();
DataTable dbSchema = cn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
if (dbSchema == null || dbSchema.Rows.Count < 1)
{
throw new Exception("Error: Could not determine the name of the first worksheet.");
}
StringBuilder sb = new StringBuilder();
sb.Append("SELECT *");
sb.Append(" FROM [" + sheetName + fieldsToRead[0].ToUpper() + startPoint + ":" + fieldsToRead[1].ToUpper() + endPoint + "] ");
OleDbDataAdapter da = new OleDbDataAdapter(sb.ToString(), cn);
dt = new DataTable(sheetName);
da.Fill(dt);
if (dt.Rows.Count > 0)
{
foreach (DataRow row in dt.Rows)
{
string i = row[0].ToString();
}
}
cn.Dispose();
return fileDatas;
}
}
catch (Exception)
{
}
}

This is for reading 2007 Excel into dataset
DataSet ds = new DataSet();
try
{
string myConnStr = "";
myConnStr = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=MyDataSource;Extended Properties=\"Excel 12.0;HDR=YES\"";
OleDbConnection myConn = new OleDbConnection(myConnStr);
OleDbCommand cmd = new OleDbCommand("select * from [Sheet1$] ", myConn);
OleDbDataAdapter adapter = new OleDbDataAdapter();
adapter.SelectCommand = cmd;
myConn.Open();
adapter.Fill(ds);
myConn.Close();
}
catch
{ }
return ds;

Read and write to Excel in c#

I am creating a test framework that should read parameters from an excel sheet. I would like to be able to :
Get a row count of test records in the sheet
Get column count
Reference a particular cell eg A23 and read or write values to it.
I found this code on the internet. Its great but it appears to have been coded to work with a form component. I dont necessarily need to show the excel sheet on a datagrid.
This is the code I found. Its working ok but I need to add the functionalities above. Thanks for your help :)
using System.Data;
using System.Data.OleDb;
...
OleDbConnection con = new OleDbConnection(#"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Book1.xls;Extended Properties=Excel 8.0");
OleDbDataAdapter da = new OleDbDataAdapter("select * from MyObject", con);
DataTable dt = new DataTable();
da.Fill(dt);

Count Row
sheet.Range["A11"].Formula = “COUNT(A1:A10)”;
Count Column
sheet.Range["A12"].Formula = “COUNT(A1:F1)”;
.NET Excel componetn

you can Reference particular cells using this code :
Select * from [Sheet1$A1:B10]
for example above code access to cell A1 to B10
see here

You can use this method:
private DataTable LoadXLS(string filePath)
{
DataTable table = new DataTable();
DataRow row;
try
{
using (OleDbConnection cnLogin = new OleDbConnection())
{
cnLogin.ConnectionString = "provider=Microsoft.Jet.OLEDB.4.0;Data Source='" + filePath + "';Extended Properties=Excel 8.0;";
cnLogin.Open();
string sQuery = "SELECT * FROM [Sheet1$]";
table.Columns.Add("Tags", typeof(string));
table.Columns.Add("ReplaceWords", typeof(string));
OleDbCommand comDB = new OleDbCommand(sQuery, cnLogin);
using (OleDbDataReader drJobs = comDB.ExecuteReader(CommandBehavior.Default))
{
while (drJobs.Read())
{
row = table.NewRow();
row["Tags"] = drJobs[0].ToString();
row["ReplaceWords"] = drJobs[1].ToString();
table.Rows.Add(row);
}
}
}
return table;
}
And use like this:
DataTable dtXLS = LoadXLS(path);
//and do what you need
If you need to write into Excel you need to check this out http://msdn.microsoft.com/en-us/library/dd264733.aspx

an easy way to handle excel files and operations to them is the following one:
add the microsoft.office.interop.excel reference to your project (Add Reference.. => search under the .NET tab => add the reference)
create a new excel application and open the workbook:
Excel.Application application = new Excel.Application();
Excel.Workbook workbook = application.Workbooks.Open(workBookPath);
Excel.Worksheet worksheet = workbook.Sheets[worksheetNumber];
you can get the row and column count with the following lines:
var endColumn = worksheet.Columns.CurrentRegion.EntireColumn.Count;
var endRow = worksheet.Rows.CurrentRegion.EntireRow.Count;***
reading values form a cell or a range of cells can be done in the following way(rowIndex is the number of the row in which the cells you want to read out are):
System.Array values = (System.Array)worksheet.get_Range("A" +
rowIndex.ToString(), "D" + rowIndex.ToString()).Cells.Value;

Convert Excel Range to ADO.NET DataSet or DataTable, etc

I have an Excel spreadsheet that will sit out on a network share drive. It needs to be accessed by my Winforms C# 3.0 application (many users could be using the app and hitting this spreadsheet at the same time). There is a lot of data on one worksheet. This data is broken out into areas that I have named as ranges. I need to be able to access these ranges individually, return each range as a dataset, and then bind it to a grid.
I have found examples that use OLE and have got these to work. However, I have seen some warnings about using this method, plus at work we have been using Microsoft.Office.Interop.Excel as the standard thus far. I don't really want to stray from this unless I have to. Our users will be using Office 2003 on up as far as I know.
I can get the range I need with the following code:
MyDataRange = (Microsoft.Office.Interop.Excel.Range)
MyWorkSheet.get_Range("MyExcelRange", Type.Missing);
The OLE way was nice as it would take my first row and turn those into columns. My ranges (12 total) are for the most part different from each other in number of columns. Didn't know if this info would affect any recommendations.
Is there any way to use Interop and get the returned range back into a dataset?

I don't know about a built-in function, but it shouldn't be difficult to write it yourself. Pseudocode:
DataTable MakeTableFromRange(Range range)
{
table = new DataTable
for every column in range
{
add new column to table
}
for every row in range
{
add new datarow to table
for every column in range
{
table.cells[column, row].value = range[column, row].value
}
}
return table
}

I don't know what type of data you have.But for an excel data like shown in this link http://www.freeimagehosting.net/image.php?f8d4ef4173.png, you can use the following code to load into data table.
private void Form1_Load(object sender, EventArgs e)
{
try
{
DataTable sheetTable = loadSingleSheet(#"C:\excelFile.xls", "Sheet1$");
dataGridView1.DataSource = sheetTable;
}
catch (Exception Ex)
{
MessageBox.Show(Ex.Message, "");
}
}
private OleDbConnection returnConnection(string fileName)
{
return new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + fileName + "; Jet OLEDB:Engine Type=5;Extended Properties=\"Excel 8.0;\"");
}
private DataTable loadSingleSheet(string fileName, string sheetName)
{
DataTable sheetData = new DataTable();
using (OleDbConnection conn = this.returnConnection(fileName))
{
conn.Open();
// retrieve the data using data adapter
OleDbDataAdapter sheetAdapter = new OleDbDataAdapter("select * from [" + sheetName + "]", conn);
sheetAdapter.Fill(sheetData);
}
return sheetData;
}

It's worth to take a look at NPOI when it comes to read/write Excel 2003 XLS files. NPOI is a life saver.
I think you'll have to iterate your range and create DataRows to put in your DataTable.
This question on StackOverflow provides more resources:
Create Excel (.XLS and .XLSX) file from C#

This method does not work well when the same column in the excel spread sheet contains both text and numbers. For instance, if Range("A3")=Hello and Range("A7")=5 then it reads only Hello and the value for Range("A7") is DBNULL
private void Form1_Load(object sender, EventArgs e)
{
try
{
DataTable sheetTable = loadSingleSheet(#"C:\excelFile.xls", "Sheet1$");
dataGridView1.DataSource = sheetTable;
}
catch (Exception Ex)
{
MessageBox.Show(Ex.Message, "");
}
}
private OleDbConnection returnConnection(string fileName)
{
return new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + fileName + "; Jet OLEDB:Engine Type=5;Extended Properties=\"Excel 8.0;\"");
}
private DataTable loadSingleSheet(string fileName, string sheetName)
{
DataTable sheetData = new DataTable();
using (OleDbConnection conn = this.returnConnection(fileName))
{
conn.Open();
// retrieve the data using data adapter
OleDbDataAdapter sheetAdapter = new OleDbDataAdapter("select * from [" + sheetName + "]", conn);
sheetAdapter.Fill(sheetData);
}
return sheetData;

I made method which can take alredy filtered data from Excel
Taking filtered data in Range format
Worksheet sheet = null;
sheet = (Worksheet)context.cDocumentExcel.Sheets[requiredSheetName];
DataTable dt = new DataTable();
sheet.Activate();
sheet.UsedRange.Select();
List<Range> ranges = new List<Range>();
Range usedrange = sheet.UsedRange;
foreach (var oneRange in usedrange.SpecialCells(XlCellType.xlCellTypeVisible))
{
ranges.Add(oneRange);
}
dt = (_makeTableFromRange(ranges));
Converting from Range to DataTable
private static DataTable _makeTableFromRange(List<Range> ranges)
{
var table = new DataTable();
foreach (var range in ranges)
{
while (table.Columns.Count < range.Column)
{
table.Columns.Add();
}
while (table.Rows.Count < range.Row)
{
table.Rows.Add();
}
table.Rows[range.Row - 1][range.Column - 1] = range.Value2;
}
//clean from empty rows
var filteredRows = table.Rows.Cast<DataRow>().
Where(row => !row.ItemArray.All(field => field is System.DBNull ||
string.Compare((field as string).Trim(), string.Empty) ==
0));
table = filteredRows.CopyToDataTable();
return table;
}