Using IDataReader for reading dbf file in C#

Question

I'm trying to read .dbf file with datareader using OleDb like this:

const string OleDbConnectionString =
    @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\mydbase;Extended Properties=dBASE IV;";
    var connection = new OleDbConnection(OleDbConnectionString);
    connection.Open();

    var command = new OleDbCommand("select * from my.dbf", connection);

    reader = command.ExecuteReader();
    Console.WriteLine(reader.Read()); // true
    Console.WriteLine(reader[0].ToString()); // exception

The exception is of InvalidCastException type and says: Unable to case from System.__ComObject to IRowset. When I tried to use OleDbAdapter to fill a table everything worked fine.
How do I read .dbf file using IDataReader?

What is that my.dbf in your select command? Should that be the table name if it is not? — kazinix
– kazinix, Commented Jul 8, 2011 at 5:59

Andreas · Accepted Answer · 2011-08-25 06:30:38Z

1

I think your path might be wrong since you have "C:\mybase" in the connectionstring and then add "my.dbf" which adds up to "C:\mybasemy.dbf".

Ill provide code how i open and read a dbf using a dataset instead of a reader.

string oledbConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\spcs\;Extended Properties=dBASE IV;User ID=Admin;Password=";

        OleDbConnection oledbConnection = new OleDbConnection(oledbConnectionString);

        string oledbQuery = @"SELECT * FROM KUND";

        try
        {
            OleDbCommand oledbCommand = new OleDbCommand(oledbQuery, oledbConnection);

            OleDbDataAdapter oledbAdapter = new OleDbDataAdapter(oledbCommand);

            DataSet oledbDataset = new DataSet();

            oledbAdapter.FillSchema(oledbDataset, SchemaType.Mapped);

            oledbConnection.Open();

            oledbAdapter.Fill(oledbDataset);

            foreach (DataRow row in oledbDataset.Tables[0].Rows)
            {
                System.Diagnostics.Trace.WriteLine(row[0].ToString());
            }
        }
        catch (Exception ex)
        {
            // Do something with ex
        }

answered Aug 25, 2011 at 6:30

Andreas

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1 Comment

StuffHappens Over a year ago

Thanks for the answer. But I need to do it with datareader, not dataset.

kazinix · Accepted Answer · 2011-07-08 06:27:34Z

0

Okay, try using GetString:

const string OleDbConnectionString =
@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\mydbase;Extended Properties=dBASE IV;";
OleDbConnection connection = new OleDbConnection(OleDbConnectionString);
connection.Open();

OleDbCommand command = new OleDbCommand("select * from my.dbf", connection);

OleDbDataReader reader = command.ExecuteReader();
Console.WriteLine(reader.Read()); // true
Console.WriteLine("{0}", reader.GetString(0)); // exception

edited Jul 8, 2011 at 6:27

answered Jul 8, 2011 at 6:02

kazinix

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4 Comments

StuffHappens Over a year ago

Select command is not an issue. I get everything worked using DataAdapter with the same connection string. I tried what you suggested - the result is the same exception.

Andreas Over a year ago

@StuffHappens I just ran your code on my own DBF and it worked, could you put the reader.GetString(0)); in a try/catch and provide the exception information? Is it a value that cannot be converted to string?

Andreas Over a year ago

@StuffHappens The first code you posted also worked for me, could this be something with your DBF file?

StuffHappens Over a year ago

yes, probably dbf file is incorrect, even though I can open it with DataAdaper.

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