学校安全横幅标语大全:DropDownList1_SelectedIndexChanged怎么用？

你的意思是不是想实现二级联动。如省市联动啊。
以下有代码。
将DropDownList1的AutoPostBack属性设为true

导入命名空间
Imports System.Data
Imports System.Data.SqlClient

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
'Dim mydb As DB
If Not IsPostBack Then
'绑定省
'Dim connstr As String = "server=.;database=mag_Web;User ID=sa;password=;"
'Dim myconn As SqlConnection
'myconn = New SqlConnection(connstr)
'myconn = mydb.GetSqlconn()
Dim myconn As SqlConnection = myconnection.GetSqlconn
myconn.Open()
Dim mycommand As New SqlCommand("select * from province", myconn)
Dim myreader As SqlDataReader
myreader = mycommand.ExecuteReader()
DropDownList1.DataSource = myreader
DropDownList1.DataTextField = "proName"

DropDownList1.DataValueField = "proID"
DropDownList1.DataBind()
myreader.Close()
'绑定市
Dim mycity As New SqlCommand("select * from city where proID=" + DropDownList1.SelectedValue, myconn)
Dim myreader1 As SqlDataReader
myreader1 = mycity.ExecuteReader()
DropDownList2.DataSource = myreader1
DropDownList2.DataTextField = "cityName"
DropDownList2.DataValueField = "cityID"
DropDownList2.DataBind()
myreader1.Close()
myconn.Close()
End If
'Dim myconn As SqlConnection

End Sub

Private Sub btnReset_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnReset.Click
txtUserName.Text = ""
txtPassword1.Text = ""
txtPassword2.Text = ""
RequiredFieldValidator1.Visible = False And RequiredFieldValidator2.Visible = False
'CompareValidator1.Visible = False

End Sub

Private Sub btnSumbit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSumbit.Click
'Dim connstr As String = "server=.;database=mag_Web;User ID=sa;password=;"

Dim myconn As SqlConnection = myconnection.GetSqlconn
'myconn = New SqlConnection(connstr)
myconn.Open()
Dim mycommand As New SqlCommand("insert into mag_Users(UserName,UserPassword,UserProvince,UserCity) values('" + txtUserName.Text + "','" + txtPassword1.Text + "','" + DropDownList1.SelectedItem.Text + "','" + DropDownList2.SelectedItem.Text + "')")
mycommand.Connection = myconn
mycommand.ExecuteNonQuery()
myconn.Close()
Response.Redirect("Login2.aspx")

End Sub

Private Sub DropDownList1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles DropDownList1.SelectedIndexChanged
Dim proID As String
proID = DropDownList1.SelectedValue
'Dim connstr As String = "server=.;database=mag_Web;User ID=sa;password=;"
Dim myconn As SqlConnection = myconnection.GetSqlconn
'myconn = New SqlConnection(connstr)
'myconn = mydb.GetSqlconn()
myconn.Open()
Dim mycommand As New SqlCommand("select * from city where proID=" + proID, myconn)
Dim myreader As SqlDataReader
myreader = mycommand.ExecuteReader()
DropDownList2.DataSource = myreader
DropDownList2.DataTextField = "cityName"

DropDownList2.DataValueField = "cityID"
DropDownList2.DataBind()
myreader.Close()
myconn.Close()

End Sub

将DropDownList1的AutoPostBack属性设为true

在DropDownList1_SelectedIndexChanged 中
将DropDownList1.SelectedValue 赋给DropDownList2