Solved

How to perform ADO.NET connection to MS Access database, place into dataset and manipulate

Posted on 2010-08-17
8
300 Views
Last Modified: 2012-05-10
Hi I've been unwittingly using ADO without realising there was a difference between that and ADO.NET.

Anyway, I just want to try and switch to ADO.NET but i'm not really sure how to do it. I've gotten as far as below... made the connection to the database and everything went fine there. What do I do from here? I guess i need to put the data into a dataset and start working with it... how do i go about this? If I have a int column called 'Int1' and a string column called 'string1' for example, how do i go about looping through, extracting data etc...

Now, I've seen a second piece of code about this which i put at the end below, which seems to show how to create a dataset... although what confuses me here is that it seems to be creating it's own connection to the database? Some help please!
'Connection to database
Dim strConnection As String = "Provider=Microsoft.Jet.OLEDB.4.0;User ID=Admin;Data Source=" & "'" & Server.MapPath("~/App_Data/CTC Database.mdb") & "'"
Dim cnnRead As OleDbDataReader
 
      strSQL = "SELECT * FROM([CTC Table])"

With cnn
         .Connection = New OleDbConnection(strConnection)
         .Connection.Open()
         .CommandText = strSQL
         cnnRead = .ExecuteReader()
End With

'Second piece of code i've seen to create a dataset
Dim da As New OleDbDataAdapter(strSQL, strConnection)
Dim ds As New DataSet()
da.Fill(ds, "Customers")

Open in new window

0
Comment
Question by:AidenA
  • 4
  • 3
8 Comments
 
LVL 4

Expert Comment

by:justin-clarke
ID: 33455732
If you use the above code you can loop through the dataset like so....


If (ds.Tables(0).Rows.Count > 0) Then

   For Each row As DataRow In ds.Tables(0).Rows

      'inside here you can access all the "rows"
      Dim strInt1 As String = row("Int1").ToString()

      Dim strString1 As String = row("String1").ToString()

   Next

End If

Open in new window

0
 

Author Comment

by:AidenA
ID: 33455787
Hi, thanks,

but as in my question... i'm just wondering also, how to get from first piece of code to second piece of code. What should i be using here... this datareader or OleDbDataAdapter? can you just link it together for me as i'm having trouble figuring it out...
0
 
LVL 4

Accepted Solution

by:
justin-clarke earned 400 total points
ID: 33455916
Sorry I see what you mean.
Dim cn As New System.Data.OleDb.OleDbConnection
Dim cm As New System.Data.OleDb.OleDbCommand
Dim strConnection As String = "Provider=Microsoft.Jet.OLEDB.4.0;User ID=Admin;Data Source=" & "'" & Server.MapPath("~/App_Data/CTC Database.mdb") & "'"

cn.ConnectionString = strConnection
cm.Connection = cn
cn.Open()
				
Dim strSQL As String = "SELECT * FROM tblTable"		

Dim da As New OleDbDataAdapter(strSQL, strConnection)
Dim ds As New DataSet()
da.Fill(ds)


'loop through the rows here


cn.Close()

Open in new window

0
Backup Your Microsoft Windows Server®

Backup all your Microsoft Windows Server – on-premises, in remote locations, in private and hybrid clouds. Your entire Windows Server will be backed up in one easy step with patented, block-level disk imaging. We achieve RTOs (recovery time objectives) as low as 15 seconds.

 
LVL 4

Expert Comment

by:justin-clarke
ID: 33455926
Think that should be OK off the top of my head.
0
 

Author Comment

by:AidenA
ID: 33456174
yeah seemed to work ok thanks.

so just one last thing then... what is cnnRead = .ExecuteReader() used for then in the above code?
0
 
LVL 18

Assisted Solution

by:John (Yiannis) Toutountzoglou
John (Yiannis) Toutountzoglou earned 100 total points
ID: 33456938
hi
for this question read this helpfull article http://blogs.x2line.com/al/archive/2007/05/01/3049.aspx
0
 

Author Comment

by:AidenA
ID: 33457090
ok thanks, so i should use in certain situations. Can't get the dataview to work though. Below is what i have... i put into a class (is that the right way to go about it?)

but doesn't work cmd.ExecuteReader throws an exception because it says 'Object reference not set to an instance of an object.' How do i create this details view properly?

'In one of my webpages where i want to create a connection

Dim objCC As New CreateConnection(strConnection, strSQL)
objCC.CreateDataView("Ref No")

'class to create connection
Public Class CreateConnection

   Public ds As New DataSet()
   Public cnnADO As OleDbConnection
   Public cmd As OleDbCommand
   Public dt As DataTable

   Public Sub New(ByVal strConnection As String, ByVal strSQL As String)

      cnnADO = New OleDbConnection(strConnection)
      cmd = New OleDbCommand(strConnection, cnnADO)
      cmd.CommandText = strSQL

      cnnADO.Open()
      Dim da As New OleDbDataAdapter(strSQL, strConnection)
      da.Fill(ds)
      
   End Sub
   Public Sub CreateDataView(ByVal strColumn)
      dt = New DataTable()
      dt = ds.Tables("CTC Table")
      dt.Load(cmd.ExecuteReader())
      Dim dv As DataView = New DataView(dt)
      dv.Sort = strColumn
   End Sub
End Class

Open in new window

0
 
LVL 4

Expert Comment

by:justin-clarke
ID: 33464205
Hi

I think you are mixing two ways of "filling" your data table.

If you take out the line:

dt.Load(cmd.ExecuteReader())

It should be OK.
0

Featured Post

Live: Real-Time Solutions, Start Here

Receive instant 1:1 support from technology experts, using our real-time conversation and whiteboard interface. Your first 5 minutes are always free.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Introduction The Visual Basic for Applications (VBA) language is at the heart of every application that you write. It is your key to taking Access beyond the world of wizards into a world where anything is possible. This article introduces you to…
As tax season makes its return, so does the increase in cyber crime and tax refund phishing that comes with it
In Microsoft Access, learn how to use Dlookup and other domain aggregate functions and one method of specifying a string value within a string. Specify the first argument, which is the expression to be returned: Specify the second argument, which …
Polish reports in Access so they look terrific. Take yourself to another level. Equations, Back Color, Alternate Back Color. Write easy VBA Code. Tighten space to use less pages. Launch report from a menu, considering criteria only when it is filled…

816 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

8 Experts available now in Live!

Get 1:1 Help Now