ขอถามเกี่ยวกับ Gridview หน่อยค่ะ ว่าเราจะกำหนดเงื่อนไขอย่างไร asp.net by vb.net

Protected Sub FindGuest()
strcon = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:\DbRegister.accdb"
con.ConnectionString = strcon
con.Open()

Dim sql As String = "SELECT CustomerName as 'ชื่อ Guest' FROM DbCustomer WHERE CustomerIntroducer = '" & Introtxt.Text & "'"

cmd = New OleDbCommand(sql, con)


Dim da As New OleDbDataAdapter(sql, con)

ds = New DataSet()

da.Fill(ds)
if ds.table(0).rows.count>0 Then
GridView1.DataSource = ds
GridView1.DataBind()
else
GridView1.visible=false
end if

End Sub

 if (GridView1.Rows.Count == 0)
                {
                    this.lbRs.Visible = true;
                }
                else
                {
                    this.lbRs.Visible = false;
                }

Protected Sub FindGuest()
        strcon = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:\DbRegister.accdb"
        con.ConnectionString = strcon
        con.Open()

        Dim sql As String = "SELECT CustomerName as 'ชื่อ Guest' FROM DbCustomer WHERE CustomerIntroducer = '" & Introtxt.Text & "'"

        cmd = New OleDbCommand(sql, con)


        Dim da As New OleDbDataAdapter(sql, con)

        ds = New DataSet()

        da.Fill(ds,"Customer")
        if ds.Tables("Customer").Rows.Count>0 Then
          GridView1.DataSource = ds
          GridView1.DataBind()
       else
           ' Do something here
       end if

    End Sub

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