asked on

datagrid does not display nothing

Hi I am just starting vb.NET and I am trying to connect to my access database and to display data in a datagrid.

i do not have any debug errors, but when I run it I can see the form and the two dataset, byt they are EMPTY !!

Imports System.Data
Imports System.Data.OleDb

Public Class StartUp
Inherits System.Windows.Forms.Form

#Region " Windows Form Designer generated code "

Public Sub New()
MyBase.New()

'This call is required by the Windows Form Designer.
InitializeComponent()

'Add any initialization after the InitializeComponent() call

End Sub

'Form overrides dispose to clean up the component list.
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
If disposing Then
If Not (components Is Nothing) Then
components.Dispose()
End If
End If
MyBase.Dispose(disposing)
End Sub

'Required by the Windows Form Designer
Private components As System.ComponentModel.IContainer

'NOTE: The following procedure is required by the Windows Form Designer
'It can be modified using the Windows Form Designer.
'Do not modify it using the code editor.
Friend WithEvents DataGrid1 As System.Windows.Forms.DataGrid
Friend WithEvents DataGrid2 As System.Windows.Forms.DataGrid
<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
Me.DataGrid1 = New System.Windows.Forms.DataGrid
Me.DataGrid2 = New System.Windows.Forms.DataGrid
CType(Me.DataGrid1, System.ComponentModel.ISupportInitialize).BeginInit()
CType(Me.DataGrid2, System.ComponentModel.ISupportInitialize).BeginInit()
Me.SuspendLayout()
'
'DataGrid1
'
Me.DataGrid1.DataMember = ""
Me.DataGrid1.HeaderForeColor = System.Drawing.SystemColors.ControlText
Me.DataGrid1.Location = New System.Drawing.Point(16, 16)
Me.DataGrid1.Name = "DataGrid1"
Me.DataGrid1.Size = New System.Drawing.Size(328, 320)
Me.DataGrid1.TabIndex = 0
'
'DataGrid2
'
Me.DataGrid2.DataMember = ""
Me.DataGrid2.HeaderForeColor = System.Drawing.SystemColors.ControlText
Me.DataGrid2.Location = New System.Drawing.Point(368, 16)
Me.DataGrid2.Name = "DataGrid2"
Me.DataGrid2.Size = New System.Drawing.Size(336, 320)
Me.DataGrid2.TabIndex = 1
'
'StartUp
'
Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
Me.ClientSize = New System.Drawing.Size(712, 358)
Me.Controls.Add(Me.DataGrid2)
Me.Controls.Add(Me.DataGrid1)
Me.Name = "StartUp"
Me.Text = "StartUp"
CType(Me.DataGrid1, System.ComponentModel.ISupportInitialize).EndInit()
CType(Me.DataGrid2, System.ComponentModel.ISupportInitialize).EndInit()
Me.ResumeLayout(False)

End Sub

#End Region

Dim cn As New OleDbConnection

Dim ds As New DataSet

Dim strSelectAuthors As String
Dim strSelectTitles As String

Dim daAuthors As New OleDbDataAdapter
Dim daTitles As New OleDbDataAdapter

Dim dtAuthors As New DataTable
Dim dtTitles As New DataTable

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

Dim strProvider As String
Dim strDataSource As String
strProvider = "Provider=Microsoft.Jet.OLEDB.4.0;"
strDataSource = "Data Source= C:\Documents and Settings\Owner\Desktop\vb tutorials\books.mdb"
cn.ConnectionString = strProvider & strDataSource

'open connection
cn.Open()

'select the dataset
strSelectAuthors = "SELECT Authors.* FROM Authors;"
strSelectTitles = "SELECT Titles.* FROM Titles;"

'link tha dataAdapter to the dataSet
daAuthors = New OleDbDataAdapter(strSelectAuthors, cn)
daTitles = New OleDbDataAdapter(strSelectTitles, cn)

'fill the dataAdapter with the DataSet and the tables
daAuthors.Fill(ds, "Authors")
daTitles.Fill(ds, "Titles")

'close the connection
cn.Close()

End Sub

Private Sub DataGrid1_Navigate(ByVal sender As System.Object, ByVal ne As System.Windows.Forms.NavigateEventArgs) Handles DataGrid1.Navigate
DataGrid1.SetDataBinding(ds, "Authors")
End Sub

Private Sub DataGrid2_Navigate(ByVal sender As System.Object, ByVal ne As System.Windows.Forms.NavigateEventArgs) Handles DataGrid2.Navigate
DataGrid1.SetDataBinding(ds, "Titles")
End Sub
End Class

amyhxu

Private Sub DataGrid1_Navigate(ByVal sender As System.Object, ByVal ne As System.Windows.Forms.NavigateEventArgs) Handles DataGrid1.Navigate
DataGrid1.DataSource = ds.Tables("Authors")
End Sub

Private Sub DataGrid2_Navigate(ByVal sender As System.Object, ByVal ne As System.Windows.Forms.NavigateEventArgs) Handles DataGrid2.Navigate
DataGrid1.DataSource = ds.Tables("Titles")
End Sub

amyhxu

actually You should set datasource in form load event:

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

Dim strProvider As String
Dim strDataSource As String
strProvider = "Provider=Microsoft.Jet.OLEDB.4.0;"
strDataSource = "Data Source= C:\Documents and Settings\Owner\Desktop\vb tutorials\books.mdb"
cn.ConnectionString = strProvider & strDataSource

'open connection
cn.Open()

'select the dataset
strSelectAuthors = "SELECT Authors.* FROM Authors;"
strSelectTitles = "SELECT Titles.* FROM Titles;"

'link tha dataAdapter to the dataSet
daAuthors = New OleDbDataAdapter(strSelectAuthors, cn)
daTitles = New OleDbDataAdapter(strSelectTitles, cn)

'fill the dataAdapter with the DataSet and the tables
daAuthors.Fill(ds, "Authors")
daTitles.Fill(ds, "Titles")

'close the connection
cn.Close()

DataGrid1.DataSource = ds.Tables("Authors")
DataGrid2.DataSource = ds.Tables("Titles")

End Sub

brillox

ASKER

Thanks amyhxu,

it works now...

it make sense.. how I can bind something if it does not have the content. I though that the .Fill was doing the job

brillox

ASKER

Do I really need 2 dataAdaptors to show two different tables or there is a short way?

amyhxu

Yes, I would use 2 dataAdapters to fill two datatables (in your case, you have "Authors", "Titles").
If you only need to get one datatable (e.g. "AuthorAndTitle") from multiple database tables, then one dataAdapter is enough.

brillox

ASKER

SO I could write something like this:

daAuthors.Fill(ds, "Authors" , "Titles")

amyhxu

No. One dataAdapter can only fill one datatable at a time.

brillox

ASKER

< If you only need to get one datatable (e.g. "AuthorAndTitle") from multiple database tables, then one dataAdapter is enough >

Can you give me an example with my two tables ?

RonaldBiemans

Amyhxu, that is not true, a dataadapter can fill multiple tabels

like

dim da as new oledb.oledbdataadapter("select * from table1; select * from table2",yourconnection)
dim ds as new dataset
da.fill(Ds)

the dataset will now be filled with 2 tables

ASKER CERTIFIED SOLUTION

amyhxu

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RonaldBiemans

Also true :-)