How to read .xlsx and .xls files using C# and OleDbConnection?

Question

Previously I was using ExcelPackage to read data out of a .xlsx file. That was working fine but then I realized that ExcelPackage doesn't work with the old .xls format. So I upgraded to using OleDbConnection instead of ExcelPackage like this:

var file = HttpContext.Current.Request.Files[0];
DataTable sheetData = new DataTable();
string connStr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" +
    file.FileName + "; Jet OLEDB:Engine Type=5;Extended Properties=\"Excel 8.0;\"";

using (OleDbConnection conn = new OleDbConnection(connStr))
{
    conn.Open();
    DataTable dtSchema = conn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, new object[] { null, null, null, "TABLE" });
    string sheetName = dtSchema.Rows[0].Field("TABLE_NAME");
    OleDbDataAdapter sheetAdapter = new OleDbDataAdapter("select * from [" + sheetName + "]", conn);
    sheetAdapter.Fill(sheetData);
}

Basically just trying to read the first spreadsheet there. But I get this error in the exception:

Cannot update. Database or object is read-only.

What am I doing wrong? Is there some type of update operation hidden in there?

Answer 1

Try this:

OleDbConnection connection;
OleDbCommand command;
OleDbDataReader dr;

        string commandText = "SELECT * FROM [Sheet1$]";
        string oledbConnectString = "Provider=Microsoft.ACE.OLEDB.12.0;" +
        @"Data Source=" + filename + ";" +
        "Extended Properties=\"Excel 12.0;HDR=YES\";";
        connection = new OleDbConnection(oledbConnectString);
        command = new OleDbCommand(commandText, connection);

        try
        {
            connection.Open();
            dr = command.ExecuteReader();

            while (dr.Read())
            {
                count++;

                for (int i = 1; i < dr.VisibleFieldCount; i++)
                {
                   Console.Writeln(""+dr[i].ToString());
                }
            }

            connection.Close();
        }
        catch (Exception ex)
        {
            MessageBox.Show("" + ex.Message);
            connection.Close();
        }

Answer 2

Below is an example method that returns a DataSet from the given excel file path. The returned DataSet should have each Excel worksheet in the workbook as a DataTable in the DataSet . This appears to work correctly, hope it may help.

private DataSet GetExcelDataSet(string path) {
  string sheetName;
  string ConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + path +
                        "; Jet OLEDB:Engine Type = 5; Extended Properties =\"Excel 8.0;\"";
  DataSet ds = new DataSet();
  using (OleDbConnection con = new OleDbConnection(ConnectionString)) {
    using (OleDbCommand cmd = new OleDbCommand()) {
      using (OleDbDataAdapter oda = new OleDbDataAdapter()) {
        cmd.Connection = con;
        con.Open();
        DataTable dtExcelSchema = con.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
        for (int i = 0; i < dtExcelSchema.Rows.Count; i++) {
          sheetName = dtExcelSchema.Rows[i]["TABLE_NAME"].ToString();
          DataTable dt = new DataTable(sheetName);
          cmd.Connection = con;
          cmd.CommandText = "SELECT * FROM [" + sheetName + "]";
          oda.SelectCommand = cmd;
          oda.Fill(dt);
          dt.TableName = sheetName;
          ds.Tables.Add(dt);
        }
      }
    }
  }
  return ds;
}