如何在VB.NET中级联3个组合框，国家，州，城市

本文介绍了如何在VB.NET中级联3个组合框，国家，州，城市的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 29岁程序员，3月因学历无情被辞！ 我对Vb.Net感兴趣的品牌newbbie。我有三个级联组合框，国家，省和市。在国家/地区组合框中进行选择时，我需要自动填充州和城市组合框。组合框从Ms Access数据库中的表中获取数据（通过外键相关）。目前国家comboBox是一个填充，而另外两个没有。我请帮助。 我尝试过： 我尝试过以下代码： mports System.Data Imports System.Configuration Imports System.Data.OleDb Public Class Form1 Dim strConn As String =Provider = Microsoft.Ace.Oledb.12.0; Data source =& Environment.CurrentDirectory& \ _Practice_Country_combo1.accdb Dim cn As New OleDbConnection（strConn） Dim Cmd As OleDbCommand Private Sub Form1_Load_1（ByVal sender As System.Object，ByVal e As System.EventArgs）Handles MyBase.Load LoadCountry（） End Sub Private Sub LoadCountry（）使用cn作为新的OleDbConnection（strConn）使用cmd作为新的OleDbCommand（）尝试使用cmd .Connection = cn .CommandType = CommandType.Text .CommandText =SELECT CountryID，Country FROM Country以$ b结尾$ b Dim ds As New DataSet（） Dim da As New OleDbDataAdapter（） da.SelectCommand = cmd cn.Open（） da.Fill（ds） cn.Close（） ComboBox1.Va lueMember =CountryID ComboBox1.DisplayMember =Country ComboBox1.DataSource = ds.Tables（0） Catch ex As Exception End Try 结束使用结束使用结束Sub Private Sub LoadProvince（ByVal countryID As Integer）使用cn作为新OleDbConnection（strConn）使用Cmd As New OleDbCommand（）尝试使用Cmd .Connection = cn .CommandType = CommandType.Text .CommandText =SELECT ProvinceID，省FROM Province WHERE CountryID =？ 以结束Cmd.Parameters.AddWithValue（？CountryID，OleDbType.Integer） Dim ds As New DataSet（） Dim da As New OleDbDataAdapter（） da.SelectCommand = Cmd cn.Open（） da.Fill（ds） cn.Close（）如果ds.Tables（0）.Rows.Count> ; 0然后 ComboBox2.ValueMember =省份ID ComboBox2.DisplayMember =省 ComboBox2.DataSource = ds.Tables（0）结束如果 Catch ex作为例外 结束尝试结束使用结束使用结束子 私有子LoadCity（ByVal ProvinceID作为整数）使用cn作为新的OleDbConnection（strConn）使用cmd作为新的OleDbCommand（）尝试使用cmd .Connection = cn .CommandType = CommandType.Text .CommandText =SELECT CityID，City FROM City WHERE ProvinceID =？ 结束 cmd.Parameters.AddWithValue（？ProvinceID，OleDbType.Integer） Dim ds As New DataSet（） Dim da As New OleDbDataAdapter（） da.SelectCommand = cmd cn.Open（） da.Fill（ds） cn.Close（）如果ds.Tables（0）.Rows.Count> ; 0然后 ComboBox3.DataSource = ds.Tables（0） ComboBox3.DisplayMember =City ComboBox3.ValueMember =CityID结束如果 Catch ex作为例外 结束尝试结束使用结束使用结束子 私人子ComboBox1_SelectedIndexChanged（ByVal发送者作为对象，ByVal e As EventArgs）如果ComboBox1.SelectedValue.ToString（）<> 然后 Dim CountryID As Integer = Convert.ToInt32（ComboBox1.SelectedValue.ToString（）） LoadProvince（CountryID） ComboBox3.SelectedIndex = 0 End if End Sub Private Sub ComboBox2_SelectedIndexChanged（ByVal sender As Object，ByVal e As EventArgs） Dim ProvinceID As Integer = Convert.ToInt32（ComboBox2.SelectedValue.ToString（）） LoadCity（ProvinceID）结束子 结束类 解决方案 只需输入如下的LoadCountry（）函数 如果 不 Page.IsPostBack 那么 LoadCountry（） 结束 如果 以及请更正命令que的参数名称ry CommandText = 选择省份ID，省份来自省份国家ID =？ to CommandText = SELECT ProvinceID，省FROM FROM WHERE CountryID =？CountryID I am brand newbbie interested in Vb.Net. I have three cascading comboBoxes , Country, Province and City. I need to have the state and city comboBoxes populated automatically when a selection is made on the country comboBox. The comboBoxes get the data from tables in Ms Access database (related through foreign keys). At the moment the country comboBox is the one populating and nothing on the other two.I Please help.What I have tried:I have tried the following code:mports System.DataImports System.ConfigurationImports System.Data.OleDbPublic Class Form1 Dim strConn As String = "Provider= Microsoft.Ace.Oledb.12.0; Data source =" & Environment.CurrentDirectory & "\Practice_Country_combo1.accdb" Dim cn As New OleDbConnection(strConn) Dim Cmd As OleDbCommand Private Sub Form1_Load_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load LoadCountry() End Sub Private Sub LoadCountry() Using cn As New OleDbConnection(strConn) Using cmd As New OleDbCommand() Try With cmd .Connection = cn .CommandType = CommandType.Text .CommandText = "SELECT CountryID, Country FROM Country" End With Dim ds As New DataSet() Dim da As New OleDbDataAdapter() da.SelectCommand = cmd cn.Open() da.Fill(ds) cn.Close() ComboBox1.ValueMember = "CountryID" ComboBox1.DisplayMember = "Country" ComboBox1.DataSource = ds.Tables(0) Catch ex As Exception End Try End Using End Using End Sub Private Sub LoadProvince(ByVal countryID As Integer) Using cn As New OleDbConnection(strConn) Using Cmd As New OleDbCommand() Try With Cmd .Connection = cn .CommandType = CommandType.Text .CommandText = "SELECT ProvinceID, Province FROM Province WHERE CountryID =?" End With Cmd.Parameters.AddWithValue("?CountryID", OleDbType.Integer) Dim ds As New DataSet() Dim da As New OleDbDataAdapter() da.SelectCommand = Cmd cn.Open() da.Fill(ds) cn.Close() If ds.Tables(0).Rows.Count > 0 Then ComboBox2.ValueMember = "ProvinceID" ComboBox2.DisplayMember = "Province" ComboBox2.DataSource = ds.Tables(0) End If Catch ex As Exception End Try End Using End Using End Sub Private Sub LoadCity(ByVal ProvinceID As Integer) Using cn As New OleDbConnection(strConn) Using cmd As New OleDbCommand() Try With cmd .Connection = cn .CommandType = CommandType.Text .CommandText = "SELECT CityID, City FROM City WHERE ProvinceID =?" End With cmd.Parameters.AddWithValue("?ProvinceID", OleDbType.Integer) Dim ds As New DataSet() Dim da As New OleDbDataAdapter() da.SelectCommand = cmd cn.Open() da.Fill(ds) cn.Close() If ds.Tables(0).Rows.Count > 0 Then ComboBox3.DataSource = ds.Tables(0) ComboBox3.DisplayMember = "City" ComboBox3.ValueMember = "CityID" End If Catch ex As Exception End Try End Using End Using End Sub Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs) If ComboBox1.SelectedValue.ToString() <> "" Then Dim CountryID As Integer = Convert.ToInt32(ComboBox1.SelectedValue.ToString()) LoadProvince(CountryID) ComboBox3.SelectedIndex = 0 End If End Sub Private Sub ComboBox2_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs) Dim ProvinceID As Integer = Convert.ToInt32(ComboBox2.SelectedValue.ToString()) LoadCity(ProvinceID) End SubEnd Class 解决方案 Just put LoadCountry() function like below If Not Page.IsPostBack Then LoadCountry() End Ifas well as please correct the parameter name of command queryCommandText = "SELECT ProvinceID, Province FROM Province WHERE CountryID =?"toCommandText = "SELECT ProvinceID, Province FROM Province WHERE CountryID =?CountryID" 这篇关于如何在VB.NET中级联3个组合框，国家，州，城市的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！ 上岸，阿里云！