VB.net Combo Box duplicate data

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I am filling in a combo box after an another combobox.text is populated. Every time the user selects the any option the first time combobox.items list populates correctly. If the user goes between items in the first box the second combobox doesnt clear so I get duplicate entries for the same option. I need help clearing the duplicate data or having the Second box clear upon change. Below is my code for populating the second box after the first one is populated. Thanks in advance.

VB

Private Sub cmbDevice_SelectedIndexChanged(sender As System.Object, e As System.EventArgs) Handles cmbDevice.SelectedIndexChanged

Dim StrQ As String = "Select [Model] from " & cmbDevice.Text & " Group By [Model] "
        Dim da As New SqlDataAdapter(StrQ, con)
        If cmbDevice.Text = "*" Then
            cmdType.Text = ""
        Else
            da.Fill(ds, cmbDevice.Text)
            With Me.cmdType
                .DataSource = ds.Tables(cmbDevice.Text)
                .DisplayMember = "Model"
                .SelectedIndex = 0
            End With
        End If

Posted 1-Dec-11 8:23am

Member 8451273

Updated 1-Dec-11 8:48am

Sander Rossel

v2

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#realJSOP · Answer 1 · 2011-12-01T09:50:00

Solution 1

Why don't you just clear the combobox.Items collection before populating it again. Alternatively, you could set the DataSource property to Nothing.

Posted 1-Dec-11 9:50am

#realJSOP

Comments

Member 8451273 1-Dec-11 15:56pm

I tried just adding combobox.Items.Clear and I get this Error: "Items collection cannot be modified when the DataSource property is set."

**Manoj K Bhoir** · Answer 2 · 2011-12-01T18:56:00

Try to clear DataSource of cmbType before Clearing Items.

VB

Private Sub cmbDevice_SelectedIndexChanged(sender As System.Object, e As System.EventArgs) Handles cmbDevice.SelectedIndexChanged
 
Dim StrQ As String = "Select [Model] from " & cmbDevice.Text & " Group By [Model] "
        Dim da As New SqlDataAdapter(StrQ, con)
        If cmbDevice.Text = "*" Then
            cmdType.Text = ""
        Else
            da.Fill(ds, cmbDevice.Text)
            cmdType.DataSource = "" ' Or you can set it as Nothing
            cmdType.Items.Clear()
            With Me.cmdType
                .DataSource = ds.Tables(cmbDevice.Text)
                .DisplayMember = "Model"
                .SelectedIndex = 0
            End With
        End If