Picker inside ListView

Hi, I have a picker that has dynamic selection, however I am struggling to save the selected value back to the DB. What command that I have to put in to refer back to its data?

<ListView> ... <Picker ItemsSource="{Binding Source={x:Reference ConfigurationPage}, Path=BindingContext.Identifier, Mode=OneWay}" ItemDisplayBinding="{Binding Item, Mode=OneWay}" SelectedItem="{Binding ????????????}" IsVisible="{Binding ConfigType, Converter={StaticResource VisibleConvertor},ConverterParameter=picker}" Grid.Column="1"/> ... </ListView>