Absolute Beginner Question

[Chris Strug]

Hi,

My apologies if this is a simple question but I'm having a hard time making
any progress so...

I'm looking at VB ADO.net, moving from ADO / Access development.

I've created a bog standard windows app in VB2005 Express and having read
some of the basics am attempting to create a connection to a SQLS2000 db on
my network and display the contents of a table in a listbox on a my form.

As I understand it, the steps involved are:
* create a connection to the database (done, I think)
* create a command object containing the action that i wish to perform
(SELECT statement)
* execute the command object and return the reults set to a DataReader
object as read-only which I can use to populate the listbox on my form.

I can create the connection and the command object but I'm not quite sure
where the datareader object comes in and how exactly I use it...

Please see code below.

I appreciate that this is a very simple question, however any and all advice
is gratefully received - be that links, pointers or so on.

Thanks

Chris.

**************************
Imports System.Data.SqlClient

Public Class Form1

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load

Dim TLCConn As SqlClient.SqlConnection
Dim contCMD As SqlClient.SqlCommand

TLCConn = New SqlConnection
TLCConn.ConnectionString = _
"Data Source=SQL;Integrated Security=SSPI;Initial
Catalog=TLCBackup"
TLCConn.Open()

contCMD = New SqlCommand
contCMD.Connection = TLCConn
contCMD.CommandText = "SELECT MovementNo, ContainerNo, DateIn,
DateOut " & _
"FROM Stock " & _
"WHERE dateout is null " & _
"ORDER BY MovementNo"
End Sub
End Class

 

[Stuart Carnie]

Dim reader as SqlDataReader

...
...

contCMD.Connection = TLCConn
contCMD.CommandText = "SELECT MovementNo, ContainerNo, DateIn, DateOut "
& _
"FROM Stock " & _
"WHERE dateout is null " & _
"ORDER BY MovementNo"

reader = contCMD.ExecuteReader()
Dim text As String

While reader.Read()
text = text + reader(0) + vbCrLf
End While

End Sub

Note: this is an example of reading the first column "reader(0)". You
should handle nulls and also should use StringBuilder for larger amounts of
concatenation. This serves only as an example.

 

[Guest]

Hi Dear Chris Strug,

here is one sample:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button1.Click


Dim oSQLConn As SqlConnection = New SqlConnection
oSQLConn.ConnectionString = "Data Source=(local);Initial
Catalog=pubs;Integrated Security=SSPI;"
Dim oSQLCommand As SqlCommand
Try
If oSQLConn.State = ConnectionState.Closed Then
oSQLConn.Open()
End If

oSQLCommand = New SqlCommand("Select * from Authors", oSQLConn)

Dim oSQLDataReader As SqlDataReader
oSQLDataReader = oSQLCommand.ExecuteReader

While (oSQLDataReader.Read())

Me.ListBox1.Items.Add(oSQLDataReader("au_lname") & " " &
oSQLDataReader("au_fname"))
End While
Catch

Finally

oSQLCommand.Dispose()

If oSQLConn.State = ConnectionState.Open Then
oSQLConn.Close()
''oSQLConn.Dispose()
End If

End Try

End Sub


here are some useful links
==================

http://msdn.microsoft.com/library/d...ntSqlConnectionClassConnectionStringTopic.asp


http://support.microsoft.com/default.aspx?scid=kb;en-us;313482

 

[Chris Strug]

Many thanks for the replies gents - thats cleared up a few things.

Next step is getting my head around the data adapter and dataset objects!

Thanks again

Chris