1. public partial class 省市县联动 : Window
   
2. {
   
3. public 省市县联动()
   
4. {
   
5. InitializeComponent();
   
6. }
   
7. 
   
8. private void Window_Loaded(object sender, RoutedEventArgs e)
   
9. {
   
10. DataTable table = SqlHelper.ExecuteDataTable("select * from Data_Province");
    
11. List<Area> list = new List<Area>();
    
12. foreach(DataRow row in table.Rows)
    
13. {
    
14. Area area=new Area();
    
15. area.Id=(string)row["ProvinceCode"];
    
16. area.Name=(string)row["ProvinceName"];
    
17. list.Add(area);
    
18. }
    
19. lbProv.ItemsSource=list;
    
20. }
    
21. 
    
22. private void lbProv_SelectionChanged(object sender, SelectionChangedEventArgs e)
    
23. {
    
24. Area area=(Area)lbProv.SelectedItem;
    
25. DataTable table=SqlHelper.ExecuteDataTable("select * from Data_City where ProvinceCode=@prov ",
    
26. new SqlParameter("@prov",area.Id));
    
27. List<Area> list=new List<Area>();
    
28. foreach (DataRow row in table.Rows)
    
29. {
    
30. Area city=new Area();
    
31. city.Id=(string)row["CityCode"];
    
32. city.Name=(string)row["CityName"];
    
33. list.Add(city);
    
34. }
    
35. lbCity.ItemsSource = list;
    
36. }
    
37. 
    
38. private void lbCity_SelectionChanged(object sender, SelectionChangedEventArgs e)
    
39. {
    
40. Area area = (Area)lbCity.SelectedItem;
    
41. DataTable table = SqlHelper.ExecuteDataTable("select * from Data_County where CityCode=@city",
    
42. new SqlParameter("@city",area.Id));
    
43. List<Area> list = new List<Area>();
    
44. foreach (DataRow row in table.Rows)
    
45. {
    
46. Area county = new Area();
    
47. county.Id = (string)row["CountyCode"];
    
48. county.Name = (string)row["CountyName"];
    
49. list.Add(county);
    
50. }
    
51. lbCounty.ItemsSource = list;
    
52. }
    
53. }
    
54. }
    

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Area类

1. class Area
   
2. {
   
3. public string Id { get; set; }
   
4. public string Name { get; set; }
   
5. }

复制代码

1.窗体加载时在lbProv列表框显示省份,当lbProv_SelectionChanged事件触发是在lbCity列表框显示市,
当lbCity_SelectionChanged事件触发是在lbCounty显示县
2.当选择一个省份后在选择一个市,接着在选择一个省份,结果出错.
当再次选择一个省份时触发lbProv_SelectionChanged事件,该省包含的所有市改变触发lbCity_SelectionChanged事件结果出错.
3.请问怎么解决?

你需要做一个判断

我记不大清楚了 当初我就遇到了这个问题

是因为获取的值是空值造成的

你需要再每次 选择变动的事件里面做一个判断

判断当前获取的值是否为空...不是空的时候再执行联动的数据库查询与数据绑定

哦 我想起来了

当你反回再次点击省之后   市的 选择变更 事件选择条目的值为空 导致数据查询还是绑定出错

OK解决了加一个判断,判断选择项是否为空.