1 using System;
2 using System.Collections.Generic;
3 using System.ComponentModel;
4 using System.Data;
5 using System.Data.SqlClient;
6 using System.Drawing;
7 using System.Linq;
8 using System.Text;
9 using System.Threading.Tasks;
10 using System.Windows.Forms;
11
12 namespace rr
13 {
14 public partial class Form1 : Form
15 {
16 public Form1()
17 {
18 InitializeComponent();
19 }
20 private void Fill1()
21 {
22 List<ChinaStates> list = new ChinaStatesDA().Select("0001");
23 comboBox1.DataSource = list;
24 comboBox1.DisplayMember = "AreaName";
25 comboBox1.ValueMember = "AreaCode";
26 }
27 private void Fill2()
28 {
29
30 string parentcode="";
31 if (comboBox1.SelectedItem!=null)
32 {
33 parentcode = (comboBox1.SelectedItem as ChinaStates).AreaCode;
34
35 }
36
37 List<ChinaStates> list = new ChinaStatesDA().Select(parentcode);
38 comboBox2.DataSource = list;
39 comboBox2.DisplayMember = "AreaName";
40 comboBox2.ValueMember = "AreaCode";
41
42 }
43 private void Fill3()
44 {
45 string parentcode = "";
46 if (comboBox2.SelectedItem != null)
47 {
48 parentcode = (comboBox2.SelectedItem as ChinaStates).AreaCode;
49
50 }
51 List<ChinaStates> list = new ChinaStatesDA().Select(parentcode);
52 comboBox3.DataSource = list;
53 comboBox3.DisplayMember = "AreaName";
54 comboBox3.ValueMember = "AreaCode";
55
56 }
57 private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
58 {
59
60 Fill3();
61 }
62
63 private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
64 {
65 Fill2();
66 Fill3();
67 }
68
69 private void Form1_Load(object sender, EventArgs e)
70 {
71 Fill1();
72 Fill2();
73 Fill3();
74 }
75 }
76 class DBcon
77 {
78 public const string CONSTR = "server=.;database=yy;uid=sa;pwd=111111";
79 }
80 class ChinaStates
81 {
82 public string AreaCode { get; set; }
83 public string AreaName { get; set; }
84 public string ParentCode { get; set; }
85 }
86 class ChinaStatesDA
87 {
88 private SqlConnection Con;
89 private SqlCommand Cmd;
90 private SqlDataReader dr;
91 public ChinaStatesDA()
92 {
93 Con = new SqlConnection(DBcon.CONSTR);
94 Cmd = Con.CreateCommand();
95 }
96 public List<ChinaStates> Select(string code)
97 {
98 List<ChinaStates> list = new List<ChinaStates>();
99 Cmd.CommandText = "select * from ChinaStates where ParentAreaCode=@code";
100 Cmd.Parameters.Clear();
101 Cmd.Parameters.AddWithValue("@code", code);
102 try
103 {
104 Con.Open();
105 dr = Cmd.ExecuteReader();
106 while (dr.Read())
107 {
108 ChinaStates data = new ChinaStates();
109 data.AreaCode = dr["AreaCode"].ToString();
110 data.AreaName = dr["AreaName"].ToString();
111 data.ParentCode = dr["ParentAreaCode"].ToString();
112 list.Add(data);
113 }
114 }
115 finally
116 {
117 Con.Close();
118 }
119
120
121 return list;
122 }
123 }
124 }
