Why is first empty line ignored in Excel import with OleDb

问题

With .Net's OleDb I try to import an Excel table in which the first row(s) can be empty. I want to keep the empty row in the DataTable to be able to map the cells to Excel-style cell names "A1, A2, ..." later. But the first line is removed, no matter what I do.

Excel file looks like:

 -   -   -
 ABC XY  ZZ
 1   2   3
 4   4   5

Where "-" is an empty cell. (I have no influence to the import format.)

Simplified code:

        string cnnStr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=\"file.xls\";Extended Properties=\"Excel 8.0;HDR=No;IMEX=1\"";
        string mySheet = "Sheet1$";

        OleDbConnection connection = new OleDbConnection(cnnStr);
        DataSet Contents = new DataSet();
        using (OleDbDataAdapter adapter = new OleDbDataAdapter("select * from [" + mySheet + "]", connection))
        {
            adapter.Fill(Contents);
        }

        Console.WriteLine(Contents.Tables[0].Rows.Count); // prints: 3
        Console.WriteLine(Contents.Tables[0].Rows[0].ItemArray[0]); // prints: ABC

Any idea how to preserve that empty row?

ps: I found How to count empty rows when reading from Excel but couldn't reproduce it.

回答1:

The issue seems to be related to the TypeGuessRows feature of the OLEDB provider. In a nutshell, data in an Excel column can be of any type. The OLEDB provider guesses the data type by scanning the first 8 rows of the sheet to determine the Majority Type - the data type with the most number of values in the sample. Anything that is not of the Majority Type are discarded.

See this blog post for a more detailed explanation.

As well as this MS KB Article that discusses the behavior.

(Skip down to the Workaround section for the TypeGuessRows behavior)

As a test, I created a file similar to the sample you posted but formatted all of the columns as text and saved the file. Running the code you posted I was able to see 4 Rows returned, with the first Row an empty string.

You may also want to try modifying the registry to see if changing the TypeGuessRows setting to 0 (scan all data in the file to determine data type of each column) helps return the first blank row. My hunch is that this won't help though.

回答2:

OleDbDataAdapter considers the first row as header. In order to get the first row, create a datarow from the header of the datatable. And insert at the first location.

  DataTable dt = Contents.Tables[0];

  DataRow dr = new DataRow();
  int i = 0;
  foreach (DataColumn column in dt.Columns)
  {
    dr[i] = column.ColumnName.ToString();
    i++;
  }
  dt.Rows.InsertAt(dr, 0);

来源：https://stackoverflow.com/questions/10010634/why-is-first-empty-line-ignored-in-excel-import-with-oledb

标签

.net

excel

oledb