Vb.net and Sqlserver

Private Sub AddButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles AddButton.Click
            con = New SqlConnection(Constr)
            con.Open()
            Dim cmdstr1 As String = "Select * from Mcdaily where Mcno='" & McnoCombo.Text & "'and Ftime=" & DGVlogentry.Item(2, i).Value & ""
            dt = DataManager.ExecuteQuery(cmdstr1, Constr)
            If (dt.Rows.Count > 0) Then
                MessageBox.Show("Already Exists")
            Else
                 Insertcmd()
             End if 
End sub