仅从绑定源中选择某些值以显示在组合框中

Question

我正在尝试操作组合框以仅显示我希望从绑定源中获得的某些值。这是我目前拥有的代码。

 provider = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source ="
    datafile = "C:\Users\Jacob\Desktop\Halton\HaltonProject.accdb"
    connString = provider & datafile
    myConnection.ConnectionString = connString
    myConnection.Open()

    Dim str As String
    str = "SELECT * FROM [Employee] WHERE (SP_Level <>  0)"
    Dim cmd As OleDbCommand = New OleDbCommand(str, myConnection)
    Dim dr As OleDbDataReader = cmd.ExecuteReader


    Dim Full_Name As String

    While dr.Read
        Full_Name = dr("Full_Name").ToString
        SP_Emp1.Items.Add(Full_Name)
        SP_Emp2.Items.Add(Full_Name)
        SP_Emp3.Items.Add(Full_Name)
        SP_Emp4.Items.Add(Full_Name)
    End while

就目前而言，此代码查看“SP_Level”并过滤掉其中列出“0”的所有员工。字符串“Full_Name”返回在“SP_Level”列中列为“0”以外的所有员工。

我想将组合框数据绑定到 EmployeeBindingSource，同时只显示由上面的代码生成的新过滤的“Full_Name”字符串。我尝试过滤绑定源，但只返回第一个匹配的字母字符串然后停止。我确定有一个简单的解决方案，我似乎找不到它

Data bound combobox

Access table used in data-binding

我对 VB 编程很陌生，因此如果措辞不当，我深表歉意。如果我能更好地解释什么，请告诉我。

Answer 1

您可以为每个行/技能集拥有/使用相同的DataSource，您只需要相应地过滤每个。这将为每个条件创建一个DataView，而不是手动从源中过滤掉一些或使用新查询来创建仅略有不同的源：

' my fake table
Dim colors As String() = {"Red", "Green", "Blue", "Orange", "White"}
Dim dt As New DataTable
dt.Columns.Add("color", GetType(String))

For Each s As String In colors
    dt.Rows.Add(s)
Next

' create a view for each level and bind it
Dim SPView As New DataView(dt, "Color <> 'Red'", "", DataViewRowState.CurrentRows)
ComboBox1.DataSource = SPView
ComboBox1.DisplayMember = "color"

Dim XPView As New DataView(dt, "Color <> 'Green'", "", DataViewRowState.CurrentRows)
ComboBox2.DataSource = XPView
ComboBox2.DisplayMember = "color"

Dim ZPView As New DataView(dt, "Color <> 'Blue'", "", DataViewRowState.CurrentRows)
ComboBox3.DataSource = ZPView
ComboBox3.DisplayMember = "color"