Object reference not set to an instance of an object.

[karan desai]

I need your kind help.
I am basically wanting to filter the data from SQL server database via VB.NET combo box to data grid view, make changes and then save them back to the database.

The thing is i am not being able to filter the data via the combobox

"Imports System.Data
Imports System.Console
Imports System.Data.SqlClient
Imports System.Data.OleDb
 
Public Class Form1
 
    Dim sqlcon As New SqlConnection
    Dim ds As New DataSet
    Dim dc As SqlCommand
    Dim daa As New SqlDataAdapter
    Dim bs As New BindingSource
    'Public Const ConnectionString As String = "Data Source=SQLORACLE;Initial Catalog=greeting;User ID=classic;password=stripes"
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        'TODO: This line of code loads data into the 'GreetingDataSet.db1' table. You can move, or remove it, as needed.
 
        Me.Db1TableAdapter.Fill(Me.GreetingDataSet.db1)
        cboest.Sorted = True
        cboest.Enabled = False
        cbover.Enabled = False
        Db1DataGridView.Visible = False
        Db1BindingNavigator.Visible = False
    End Sub
 
    Private Sub Db1BindingNavigatorSaveItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Db1BindingNavigatorSaveItem.Click
        Me.Validate()
        Me.Db1BindingSource.EndEdit()
        Me.Db1TableAdapter.Update(Me.GreetingDataSet.db1)
    End Sub
 
    Private Sub cmdselect_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdselect.Click
 
// filtering the according to "estno"
 
 
        Dim cbostr
        cbostr = Me.cboest.Text
        Dim dv As DataView
        dv = ds.Tables("db1").DefaultView
        dv.RowFilter = "estno like = " & cbostr
        cboest.Enabled = True
        cmdselect.Enabled = False
    End Sub
 
    Private Sub cboest_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboest.SelectedIndexChanged
 
        cbover.Enabled = True
    End Sub
 
    Private Sub cbover_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cbover.SelectedIndexChanged
        cboest.Enabled = False
        cbover.Enabled = False
        cmdselect.Enabled = True
        Db1DataGridView.Visible = True
        Db1BindingNavigator.Visible = True
    End Sub
End Class"

My code may be wrong or mistaken, for which I need your help.
Please reply

[David Gluth]

try changing lline 41 to use % filters. In SQL the way you have have coded the 'like' it would act like'='.

dv.RowFilter = "estno like = %" & cbostr & "%"

[karan desai]

Thanks a lot
it's working.