DropDownList二级联动的问题
数据库里有两个表,province(province_id和province_name)和city(city_id,city_name,province_id)
我的代码是这么写的
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'在此处放置初始化页的用户代码
If Not IsPostBack Then
Province_Bind()
Province_SelectedIndexChanged()
End If
End Sub
Sub Province_Bind()
Dim DS As New DataSet
Dim MyConnection As New OleDbConnection
Dim MyCmd As New OleDbDataAdapter
MyConnection = New OleDbConnection("Provider=Microsoft.Jet.Oledb.4.0;Data Source=" + Server.MapPath("../data/db.mdb"))
MyCmd = New OleDbDataAdapter("Select Province_id,Province_name From Province", MyConnection)
DS = New DataSet
MyCmd.Fill(DS, "Province")
Province.DataSource = DS.Tables("Province").DefaultView
Province.DataValueField = "province_id"
Province.DataTextField = "province_name"
Province.DataBind()
End Sub
Sub Province_SelectedIndexChanged()
Dim DS As New DataSet
Dim MyConnection As New OleDbConnection
Dim MyCmd As New OleDbDataAdapter
MyConnection = New OleDbConnection("Provider=Microsoft.Jet.Oledb.4.0;Data Source=" + Server.MapPath("../data/db.mdb"))
MyCmd = New OleDbDataAdapter("Select City_ID, City_Name From City Where Province_ID='" & Province.SelectedItem.Value & "'", MyConnection)
DS = New DataSet
MyCmd.Fill(DS, "City")
City.DataSource = DS.Tables("City").DefaultView
City.DataValueField = "City_ID"
City.DataTextField = "City_Name"
City.DataBind()
End Sub
End Class
运行提示出错:System.Data.OleDb.OleDbException: 标准表达式中数据类型不匹配。我也不知道我这么写对不对,谁能给指点一下!