Question

在我的一个vb页面中，我通过会话中的值设置文本框的值。在同一页面中，我想执行记录的编辑操作。在页面加载时，我在文本框中显示变量，在我提交并从文本框中获取值后编辑值后，它仍然采用我通过会话设置的值。它不会在文本框中更改值，而是显示页面加载时分配的值。请帮忙。

这是我的代码，

Imports System.Data
Imports System.Data.SqlClient
Imports System.Web.SessionState.HttpSessionState
Imports System.Drawing
Imports System.Drawing.Printing
Partial Class Default2
    Inherits System.Web.UI.Page
    Dim cn As New SqlConnection
    Dim cmd As New SqlCommand
    Dim dr As SqlDataReader
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        cn = New SqlConnection("Data Source=nnn-PC;Initial Catalog=Faculty Housing;Persist Security Info=True;User ID=sa;Password=nnn;")
        cn.Open()
        Dim var As String
        var = Session("S2").ToString()
        TextBox1.Text = var
        Session.Remove("S2")
        cmd = New SqlCommand("select * from HouseDetails where OccupantName= '" & TextBox1.Text & "' ", cn)
        dr = cmd.ExecuteReader
        While (dr.Read)
            Label1.Text = dr(1)
            Label2.Text = dr(2)
            Label3.Text = dr(3)
            TextBox3.Text = dr(4)
            DropDownList3.SelectedItem.Text = dr(5)
            TextBox2.Text = dr(6)
            TextBox4.Text = dr(7)
            TextBox5.Text = dr(8)
            DropDownList4.Text = dr(9)
        End While
        cn.Close()

    End Sub

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click

        cn = New SqlConnection("Data Source=nnn-PC;Initial Catalog=Faculty Housing;Persist Security Info=True;User ID=sa;Password=nnn;")
        cn.Open()
        Dim query As String = ("UPDATE HouseDetails SET OccupantName='" & TextBox1.Text & "' where HouseNum='" & Label3.Text & "'")
        cmd = New SqlCommand(query, cn)
        Dim x As Integer = cmd.ExecuteNonQuery()
        cn.Close()

    End Sub

    Protected Sub TextBox1_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged

    End Sub
End Class

Answer 1

我想你错过了IsPostBack支票，看看这是新请求还是提交。

If (Not IsPostBack) Then
  ' populate for first load
End If

Answer 2

您必须将代码放在IsPostback属性中。

Imports System.Data
Imports System.Data.SqlClient
Imports System.Web.SessionState.HttpSessionState
Imports System.Drawing
Imports System.Drawing.Printing
Partial Class Default2
    Inherits System.Web.UI.Page
    Dim cn As New SqlConnection
    Dim cmd As New SqlCommand
    Dim dr As SqlDataReader
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

If (!IsPostBack) Then
        cn = New SqlConnection("Data Source=nnn-PC;Initial Catalog=Faculty Housing;Persist Security Info=True;User ID=sa;Password=nnn;")
        cn.Open()
        Dim var As String
        var = Session("S2").ToString()
        TextBox1.Text = var
        Session.Remove("S2")
        cmd = New SqlCommand("select * from HouseDetails where OccupantName= '" & TextBox1.Text & "' ", cn)
        dr = cmd.ExecuteReader
        While (dr.Read)
            Label1.Text = dr(1)
            Label2.Text = dr(2)
            Label3.Text = dr(3)
            TextBox3.Text = dr(4)
            DropDownList3.SelectedItem.Text = dr(5)
            TextBox2.Text = dr(6)
            TextBox4.Text = dr(7)
            TextBox5.Text = dr(8)
            DropDownList4.Text = dr(9)
        End While
        cn.Close()
  End If
    End Sub

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click

        cn = New SqlConnection("Data Source=nnn-PC;Initial Catalog=Faculty Housing;Persist Security Info=True;User ID=sa;Password=nnn;")
        cn.Open()
        Dim query As String = ("UPDATE HouseDetails SET OccupantName='" & TextBox1.Text & "' where HouseNum='" & Label3.Text & "'")
        cmd = New SqlCommand(query, cn)
        Dim x As Integer = cmd.ExecuteNonQuery()
        cn.Close()

    End Sub

    Protected Sub TextBox1_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged

    End Sub
End Class

Answer 3

使用“If（Page.IsPostBack = false）Then”行添加回发预防，以便不再将相同的值分配给文本框，

Imports System.Data
Imports System.Data.SqlClient
Imports System.Web.SessionState.HttpSessionState
Imports System.Drawing
Imports System.Drawing.Printing
Partial Class Default2
    Inherits System.Web.UI.Page
    Dim cn As New SqlConnection
    Dim cmd As New SqlCommand
    Dim dr As SqlDataReader
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

If (Page.IsPostBack = false) Then
        cn = New SqlConnection("Data Source=nnn-PC;Initial Catalog=Faculty Housing;Persist Security Info=True;User ID=sa;Password=nnn;")
        cn.Open()
        Dim var As String
        var = Session("S2").ToString()
        TextBox1.Text = var
        Session.Remove("S2")
        cmd = New SqlCommand("select * from HouseDetails where OccupantName= '" & TextBox1.Text & "' ", cn)
        dr = cmd.ExecuteReader
        While (dr.Read)
            Label1.Text = dr(1)
            Label2.Text = dr(2)
            Label3.Text = dr(3)
            TextBox3.Text = dr(4)
            DropDownList3.SelectedItem.Text = dr(5)
            TextBox2.Text = dr(6)
            TextBox4.Text = dr(7)
            TextBox5.Text = dr(8)
            DropDownList4.Text = dr(9)
        End While
        cn.Close()
  End If
    End Sub

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click

        cn = New SqlConnection("Data Source=nnn-PC;Initial Catalog=Faculty Housing;Persist Security Info=True;User ID=sa;Password=nnn;")
        cn.Open()
        Dim query As String = ("UPDATE HouseDetails SET OccupantName='" & TextBox1.Text & "' where HouseNum='" & Label3.Text & "'")
        cmd = New SqlCommand(query, cn)
        Dim x As Integer = cmd.ExecuteNonQuery()
        cn.Close()

    End Sub

    Protected Sub TextBox1_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged

    End Sub
End Class

在文本框中设置的VB点网络会话值不会更改

3 个答案: