Question

I must have missed something here. I am trying to create a table but I am getting an error telling me that connection is still open. But where??? I have re-read the code but I can’t find where the connection is still open…

Problem lays here: objOleDbConnection.Open()

Error say:

You attempted to open a database that is already opened by user 'Admin' on machine 'machine'. Try again when the database is available.

private void sfdNewFile_FileOk(object sender, System.ComponentModel.CancelEventArgs e)
{
    // Creating a ADOX object needed to create
    // new MS Access file.
    ADOX.Catalog createMSFile = new ADOX.Catalog();
    // Creating an object for a table.
    Table nTable = new Table();

    // Creating an object allowing me connecting to the database.
    OleDbConnection objOleDbConnection = new OleDbConnection();
    objOleDbConnection.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;" +
            "Data Source=" + sfdNewFile.FileName + ";Persist Security Info=False;Mode=12";
    // Creating command object.
    OleDbCommand objOleDbCommand = new OleDbCommand();
    objOleDbCommand.Connection = objOleDbConnection;

    try
    {
        // Created a new MS Access 2007 file with specified path.
        createMSFile.Create("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" +
            sfdNewFile.FileName);

        objOleDbConnection.Open();
        objOleDbCommand.CommandText = "CREATE TABLE PersonalData (" +
            "[DataID] AUTOINCREMENT NOT NULL PRIMARY KEY ," +
            "[Type] VARCHAR(40) NOT NULL ," +
            "[URL] VARCHAR(40) NOT NULL ," +
            "[SoftwareName] VARCHAR(40) NOT NULL ," +
            "[SerialCode] VARCHAR(40) NOT NULL ," +
            "[UserName] VARCHAR(40) NOT NULL ," +
            "[Password] VARCHAR(40) NOT NULL";

        objOleDbCommand.ExecuteNonQuery();
    }
    catch (Exception ex)
    {
        // Displaying any errors that 
        // might have occured.
        MessageBox.Show("Error: " + ex.Message);
    }
    finally
    {
        // It is importnat to release COM object, in this very order
        // otherwise we eill end up with an error.
        System.Runtime.InteropServices.Marshal.FinalReleaseComObject(createMSFile);

        // Closing the connection to the database.
        objOleDbConnection.Close();
    }
}

Answer 1

It seems that the ADOX object should close its connection as well.
Look at the following sample from Microsoft:
http://msdn.microsoft.com/en-us/library/windows/desktop/ms681562(v=vs.85).aspx

Their ADOX object is named cat.
They have the following:

cat.ActiveConnection = Nothing

Which will probably translate to:

createMSFile.ActiveConnection = null

In your code (probably in the first Finally block).
I think it’s the ADOX object that makes the difference, before dispoing it, try to set it’s ActiveConnection to null.