Table Field must appears as ComboBox in a Form - visual-studio-2010

Question

I have a form that helps me to see the records of CUSTOMERS. I use nextRecord and PreviousRecord to browse this table CUSTOMERS.
Also I have a table of CITIES. Two tables are relationed (1 cities -- n Customers)
One of the fields in the customer table is CITY. Now the field in the form is a TextBox but I need this field in the form is a ComboBox to change the city customer doing click in the combo that will show all the cities included in the table CITIES.
When I display the data of a customer the Combo must be positioned in the correct city of customer, I mean if the city of customer is London the combo must show London, when I click the combo we will see all the cities...
Thanks in advance!

Answer 1

I am not sure what language you are using. Please update your question so we know what you are working in and what you have come up with so far.
In case you are working in C# and have a table in a WPF window you can display your data in a Datagrid and define a custom resource.
Something like this:
<DataGrid.Resources>
<DataTemplate x:Key="CitiesTemplate">
<StackPanel Orientation="Horizontal" >
<Label Content="{Binding City, Mode=OneWay}" Visibility="{Binding Cities, Converter={StaticResource ResourceKey=labelVisibilityConverter}}" />
<ComboBox ItemsSource="{Binding Cities, Mode=OneWay}" DisplayMemberPath="City.Name" SelectedIndex="0" SelectionChanged="cbCity_SelectionChanged"
Visibility="{Binding Cities, Converter={StaticResource ResourceKey=comboboxVisibilityConverter}}" />
</StackPanel>
</DataTemplate>
<DataTemplate x:Key="EditingCitiesTemplate">
<StackPanel Orientation="Horizontal" >
<Label Content="{Binding City, Mode=OneWay}" Visibility="{Binding Cities, Converter={StaticResource ResourceKey=labelVisibilityConverter}}" />
<ComboBox ItemsSource="{Binding Cities, Mode=OneWay}" DisplayMemberPath="City.Name"
Visibility="{Binding Cities, Converter={StaticResource ResourceKey=comboboxVisibilityConverter}}" />
</StackPanel>
</DataTemplate>
And then define a DataGrid column like this:
<DataGrid.Columns>
<DataGridTemplateColumn Header="City" CellTemplate="{StaticResource CitiesTemplate}" CellEditingTemplate="{StaticResource EditingCitiesTemplate}" />
</DataGrid.Columns>
Then you have to define the SelectionChanged event in code that handles DB updating with the selected city.