Newbie Wants to get row from database based on combobox selection

[Bomac8]

I get the error message "object reference not set to the instance if an object". The code that I have is :

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
 
        LoadName()
 
        Dim con As New OleDbConnection
        con.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=..\CCS.mdb"
 
        Try
            con.Open()
 
            Dim daGuard As OleDbDataAdapter = New OleDbDataAdapter("select gID, fullName from tblGuardInfo", con)
            Dim dt As New DataSet
            daGuard.Fill(dt, "tblGuardInfo")
            Me.cboGetGuard.DataSource = dt.Tables("tblGuardInfo").DefaultView
            Me.cboGetGuard.DisplayMember = "fullName"
            Me.cboGetGuard.ValueMember = "fullName"
 
            dt = Nothing
            daGuard = Nothing
 
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        Finally
            con.Close()
        End Try
 
    End Sub
 
    Private Sub btnGetInfo_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnGetInfo.Click
 
        Dim con As New OleDbConnection
        con.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=..\CCS.mdb"
        Dim strSQL As String = "SELECT gID,gFName,gLName from tblGuardInfo WHERE fullName = '" & Me.cboGetGuard.Text & "'"
 
        Try
            con.Open()
 
            Dim daGuard As OleDbDataAdapter = New OleDbDataAdapter(strSQL, con)
            Dim dsGuard As New DataSet
            daGuard.Fill(dsGuard)
            Me.cboGetGuard.DataSource = dsGuard.Tables("tblGuardInfo")
 
            Me.txtgID.Text = dsGuard.Tables("tblGuardInfo").Rows(0).Item("gID")
            Me.txtgFName.Text = dsGuard.Tables("tblGuardInfo").Rows(0).Item("gFName")
            Me.txtgLName.Text = dsGuard.Tables("tblGuardInfo").Rows(0).Item("gLName")
 
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try
    End Sub
 
    Private Sub LoadName()
        Me.lblFullName.Text = Me.cboGetGuard.Text
    End Sub

[Shashi Sadasivan]

And which one of those lines throws that exception?

[kunal pawar]

I think error is in
LoadName() function
coz cboGetGuard is combo obx or dropdown and u used property
cboGetGuard.text

[Bomac8]

the exception iss thrown after executing this line:

Me.txtgID.Text = dsGuard.Tables("tblGuardInfo").Rows(0).Item("gID")

However, during debugging, i dont think there is anything in the dataset.

Why am i getting the "object reference not set to the instance if an object" error?
Me.cboGetGuard.DataSource = dsGuard.Tables("tblGuardInfo")

[Plater]

If the query does not return any rows, then your table will be empty and calling Rows(0) will throw that exception.