如何填充ComboBox并根据StateID搜索设置选中索引

你之前的问题在于ComboBox里只存了州名，没有关联对应的StateID，所以没法直接通过ID匹配选中项。下面给你两种简单可行的实现方式：

方案一：用DataTable作为数据源（最适合数据库场景） #

直接查询时同时获取StateID和State字段，把DataTable绑定到ComboBox，指定显示和值的字段：

' 填充ComboBox的代码修改为
Dim dt As New DataTable()
cmd.Connection = conn
cmd.CommandText = "SELECT StateID, State FROM States WHERE ActiveEntry = true ORDER BY State"

conn.Open()
dt.Load(cmd.ExecuteReader())
conn.Close()

cb_State.DataSource = dt
cb_State.DisplayMember = "State" ' ComboBox显示的文本
cb_State.ValueMember = "StateID" ' 背后关联的ID值
cb_State.SelectedIndex = -1

当加载客户数据拿到customerStateID（对应客户表的StateID）后，直接设置SelectedValue就能选中对应州：

' 假设customerStateID是从客户表查询得到的整数
cb_State.SelectedValue = customerStateID

方案二：用自定义类存储州信息 #

如果不想用DataTable，可以自定义一个类来保存StateID和州名，再绑定到ComboBox：

1. 定义StateItem类 #

Public Class StateItem
    Public Property StateID As Integer
    Public Property StateName As String
    
    ' 重写ToString，让ComboBox默认显示州名
    Public Overrides Function ToString() As String
        Return StateName
    End Function
End Class

2. 填充ComboBox #

Dim stateList As New List(Of StateItem)()
cmd.Connection = conn
cmd.CommandText = "SELECT StateID, State FROM States WHERE ActiveEntry = true ORDER BY State"

conn.Open()
Using rdr As OleDbDataReader = cmd.ExecuteReader()
    While rdr.Read()
        stateList.Add(New StateItem() With {
            .StateID = CInt(rdr("StateID")),
            .StateName = rdr("State").ToString()
        })
    End While
End Using
conn.Close()

cb_State.DataSource = stateList
cb_State.ValueMember = "StateID"
cb_State.DisplayMember = "StateName"
cb_State.SelectedIndex = -1

3. 设置选中项 #

同样通过SelectedValue匹配StateID：

cb_State.SelectedValue = customerStateID

这两种方法都不需要额外查询States表拿州名，直接通过StateID就能完成选中操作，比你之前想的FindString方法更高效合理。

内容的提问来源于stack exchange，提问作者Gary L Smith