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vb.net dataset errors connecting to SQL server and displaying fields on form.

New to SQL and VB.Net but have used Access and VBA for years. I have a couple of questions regarding the code below. I get an error saying there is no row at position 0. I don't even know what that means, let alone what to do about it. Also, I have 3 comboboxes on the form I am trying to populate. They fill automatically when the form loads, but I want them to select the item that represents the specific record in the database. For example: I have 10 stores in the dropdown, but the record I am trying to retrieve is associated with the ID 5. It's DisplayMember is the name of the store, but its ValueMember is an ID. I want the combobox to select the the ID associated with the record in SQL and then display the DisplayMember correctly. Can I do this? Here is the code:
Public Sub psFillDataset()
Dim conn As New SqlConnection(sqlComm)
Try
Dim sSQL As String
sSQL = "Select * from tvwLeads where numLeadID=" & numSelected & " order by numLeadID"
MsgBox(numSelected)
Dim dbadp As New SqlDataAdapter(sSQL, sqlComm)
Dim dTable As New DataTable
dbadp.Fill(dTable)
dbadp.Dispose()
Me.txtSource.DataSource = dTable
Me.txtType.Text = ("strType").ToString()
Me.txtClient.Text = ("numClient").ToString()
Me.txtLast.Text = dTable.Rows(0)("strLast").ToString()
Me.txtFirst.Text = dTable.Rows(0)("strFirst").ToString()
Me.tmTO.Text = dTable.Rows(0)("tmTO").ToString()
Me.dtTO.Text = dTable.Rows(0)("dtTO").ToString()
Me.tmCT.Text = dTable.Rows(0)("tmCTC").ToString()
Me.dtCT.Text = dTable.Rows(0)("dtCTC").ToString()
Me.chkBad.Text = dTable.Rows(0)("ysnBad").ToString()
Me.txtManager.Text = dTable.Rows(0)("strManager").ToString()
Me.cboSales.Text = dTable.Rows(0)("strName").ToString()
Me.txtNotes.Text = dTable.Rows(0)("strNotes").ToString()
Me.txtEmail.Text = dTable.Rows(0)("strResponse").ToString()
Me.txtID.Text = dTable.Rows(0)("numLeadID").ToString()
Me.txtSource.DisplayMember = "strSource"
Me.cboVehicle.DisplayMember = "strLeadType"
Catch ex As Exception
MsgBox(ex.Message)
End Try

End Sub

smm6809

Asked: 2016-07-20

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1 Solution

LVL 71

Éric MoreauSenior .Net ConsultantCommented: 2016-07-20

>> I get an error saying there is no row at position 0

that means that your select query returns no row and you are trying to update the first row (index = 0)

smm6809Author Commented: 2016-07-20

Thanks, I was using the wrong table. More importantly to me is what I'm trying to do with the comboboxes. Possible?

LVL 71

Éric MoreauSenior .Net ConsultantCommented: 2016-07-20

how are you filling the combo boxes with all the various available values? They need to be fed somewhere (often in the form load). Once fed, you can set the current value like this:

Me.cboVehicle.SelectedValue = dTable.Rows(0)("yourvehicleidvariable")

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check https://msdn.microsoft.com/en-us/library/system.windows.forms.listcontrol.selectedvalue(v=vs.110).aspx

smm6809Author Commented: 2016-07-20

Thank you so much! One last question. These two fields are not displaying the value in the textbox. They are displaying strType and numClient. However, the information is in the database and the field names are correctly spelled. Any thoughts?

Me.txtType.Text = ("strType").ToString()
Me.txtClient.Text = ("numClient").ToString()

LVL 71

Éric MoreauSenior .Net ConsultantCommented: 2016-07-20

because you simply set those values!

your code surely needs to be:

Me.txtType.Text = dTable.Rows(0)("strType").ToString()
 Me.txtClient.Text = dTable.Rows(0)("numClient").ToString()

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smm6809Author Commented: 2016-07-20

Haha so I did! How do I choose the best solution from you when they all helped? And thank you!

smm6809Author Commented: 2016-07-20

Some of my comboboxes still not populating, but they're just filled in with items, not connected to the database. Do I still handle them the same with selected value? If so, they aren't working. Also, I have 2 checkboxes that arent populating. The database shows them as 0s and 1s. Are they handled differently?

LVL 71

Éric MoreauSenior .Net ConsultantCommented: 2016-07-20

how and where do you feed those combos?

as for checkboxes, you need special code:

Me.chkBad.Checked = (dTable.Rows(0)("ysnBad").ToString() = "1")

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smm6809Author Commented: 2016-07-20

Thanks. This is how I fill the comboboxes on the ones that aren't populating:
cboVehicle.Items.Clear()
cboVehicle.DisplayMember = "Text"
cboVehicle.Items.Add(New With {.Text = "NEW"})
cboVehicle.Items.Add(New With {.Text = "USED"})

cboContact.Items.Clear()
cboContact.DisplayMember = "Text"
cboContact.Items.Add(New With {.Text = "LE"})
cboContact.Items.Add(New With {.Text = "L/M & LE"})
cboContact.Items.Add(New With {.Text = "Not Determined"})
cboContact.Items.Add(New With {.Text = "YES"})
cboContact.Items.Add(New With {.Text = "NO"})

Then I use Me.cboContact.SelectedValue = dTable.Rows(0)("strContact").ToString()
Me.cboVehicle.SelectedValue = dTable.Rows(0)("strVehicle").ToString()
to put them back into the form.

LVL 71

Éric MoreauSenior .Net ConsultantCommented: 2016-07-20

in this case, you can simplify the syntax to:

cboVehicle.Items.Clear()
cboVehicle.Items.Add("NEW")
cboVehicle.Items.Add("USED")

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then you will be able to use:

Me.cboVehicle.Text = dTable.Rows(0)("strLeadType").tostring

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smm6809Author Commented: 2016-07-20

Perfect, but checkboxes still not working. If I'm understanding you correctly, I place that code in the same spot as all the other code we worked on and if it is a 1 in the database, it should show as checked on the form. If so, it isn't showing as such. Also, if there is a null value will I get the message that there is no row at position 0? I am getting it for certain records that I know have some data but not all of the fields. How do you handle that?

LVL 71

Éric MoreauSenior .Net ConsultantCommented: 2016-07-20

NULLs are a special value and you need to process them specially! You won't get an exception saying that there is no row at position 0 because this is really when there are no rows in your datatable.

To check for NULLs, you should:

if dTable.Rows(0)("strType") isnot nothing then
     Me.txtType.Text = dTable.Rows(0)("strType").ToString()
end if

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For checkboxes, you can try:

if dTable.Rows(0)("ysnBad") is nothing orelse dTable.Rows(0)("ysnBad").ToString() = "0") then
   Me.chkBad.Checked = false
else
   Me.chkBad.Checked = true
end if

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smm6809Author Commented: 2016-07-20

That code looks exactly right but now it checks the boxes are always checked. Ugh, I want to go back to VBA. Do you know a good book that gets into this level of coding?

LVL 71

Éric MoreauSenior .Net ConsultantCommented: 2016-07-20

what do you get if you do :

messagebox.show(dTable.Rows(0)("ysnBad").ToString())

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chances are that you won't see 0 and 1 like you told me before!

smm6809Author Commented: 2016-07-20

Got error before running: argument not specified for parameter "Prompt" of "Publci Function MsgBox(Prompt as Object,[Buttons as MsgboxStyle=ApplicationModal],Title As Object=Nothing]) as MsgBoxResult

LVL 71

Éric MoreauSenior .Net ConsultantCommented: 2016-07-20

can you copy here your code? because mine is not using msgbox!

smm6809Author Commented: 2016-07-20

Re-pasted what you sent. I get true, so I fixed the code. I appreciate your time today.

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vb.net dataset errors connecting to SQL server and displaying fields on form.

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