Better way to print out rows from a datatable in vb.net - vb.net

Question

I am new to vb.net and I am trying to query a database and print out the records in the row to the console window. I got it to work, but I have a feeling that there is a more concise way to do this. One thing that I am sure is wrong is that I had to convert the dataset to a datatable to be able to retrieve the values. Is that correct? Could you take a look at the code below (especially the for loop) and let me know what I can improve upon?
Thanks!
Module Module1
Sub Main()
Dim constring As String = "Data Source=C:\Users\test\Desktop\MyDatabase1.sdf"
Dim conn As New SqlCeConnection(constring)
Dim cmd As New SqlCeCommand("SELECT * FROM ACCOUNT")
Dim adapter As New SqlCeDataAdapter
Dim ds As New DataSet()
Try
conn.Open()
cmd.Connection = conn
adapter.SelectCommand = cmd
adapter.Fill(ds, "testds")
cmd.Dispose()
adapter.Dispose()
conn.Close()
Dim dt As DataTable = ds.Tables.Item("testds")
Dim row As DataRow
Dim count As Integer = dt.Columns.Count()
For Each row In dt.Rows
Dim i As Integer = 0
While i <= count - 1
Console.Write(row(i))
i += 1
End While
Console.WriteLine(Environment.NewLine())
Next
Catch ex As Exception
Console.WriteLine("There was an error")
Console.WriteLine(ex)
End Try
Console.ReadLine()
End Sub
End Module

Answer 1

Here is how I would rewrite this for a few reasons:
1) You should always use Using statements with disposable objects to ensure they are correctly cleaned up. You had a good start with the dispose commands, but this way is safer.
2) It is more efficient to use ExecuteReader than loading everything into a dataset.
3) Your try/catch statement should include object creation as well as execution.
Finally, in response to your question about datasets and datatables, that code was absolutely correct: a dataset consists of zero or more datatables, so you were just extracting the existing datatable from the dataset.
Try
Dim constring As String = "Data Source=C:\Users\test\Desktop\MyDatabase1.sdf"
Using conn As New SqlCeConnection(constring)
conn.Open()
Using cmd As New SqlCeCommand("SELECT * FROM ACCOUNT", conn)
Dim reader As SqlCeDataReader
reader = cmd.ExecuteReader()
Do While reader.Read
For i As Integer = 0 To reader.FieldCount - 1
Console.Write(reader.GetString(i))
Next
Console.WriteLine(Environment.NewLine())
Loop
End Using
End Using
Catch ex As Exception
Console.WriteLine("There was an error")
Console.WriteLine(ex)
End Try
Console.ReadLine()
End Sub
One last note: since you are just printing to the console, it doesn't matter as much, but whenever you deal with a lot of strings, especially those that are to be concatenated, you should always consider using System.Text.StringBuilder.
Here is an example rewrite of the loop that prints to the console using stringbuilder (builds the string in memory, then dumps it to the console; I have also added the field name for good measure):
Dim sbOutput As New System.Text.StringBuilder(500)
For i As Integer = 0 To reader.FieldCount - 1
If sbOutput.Length <> 0 Then
sbOutput.Append("; ")
End If
sbOutput.Append(reader.GetName(i)).Append("=").Append(reader.GetString(i))
Next
sbOutput.AppendLine()
Console.Write(sbOutput.ToString)