Question

我有一个包含6个组框的表单，每个组框包含180个文本框，以及两个组合框。在从第一个组合框中选择一个值时，第二个组合框将从表中填充所需的数据。我的要求是，在从第二个组合框中选择一个值时，来自同一个表的过滤数据应该填充剩余的文本框。我使用的代码如下：

    Private Sub ComboBox2_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox2.SelectedIndexChanged
    Dim strConnection As String = "Provider=Microsoft.Jet.OleDb.4.0; Data Source=c:\\users\\brisingr\\documents\\123\database.mdb"
    Dim objConnection As New OleDbConnection(strConnection)

    Dim strsql As String
    'strsql = "Select * from '" & ComboBox1.Text & "' where Style = '" & ComboBox2.Text & " '"
    Dim a As String
    Dim b As String
    Dim c As String
    Dim d As String
    a = "Select * from ["
    b = ComboBox1.Text
    c = "] where Style = ["
    d = ComboBox2.Text
    strsql = a & b & c & d & "]"
    Dim objCommand As New OleDbCommand(strsql, objConnection)

    Dim objDataAdapter As New OleDbDataAdapter(objCommand)
    Dim objDataTable As New DataTable("Buyers")
    objDataAdapter.Fill(objDataTable)

    objConnection.Close()
    objConnection.Dispose()
    objConnection = Nothing
    objCommand.Dispose()
    objCommand = Nothing
    objDataAdapter.Dispose()
    objDataAdapter = Nothing

    For i As Integer = 1 To 60
        Me.Controls("L1Ob" & i).Text = objDataTable.Rows(0)("Operation" & i)
    Next

End Sub

这里“操作”＆amp; （i）引用数据库的字段名称，其名称类似于operation1，operation2等......

此代码似乎对我不起作用。请帮忙..

Answer 1

这里有很多问题

Dim a As String
Dim b As String
Dim c As String
Dim d As String
a = "Select * from ["
b = ComboBox1.Text
c = "] where Style = ["
d = ComboBox2.Text
strsql = a & b & c & d & "]"
Dim objCommand As New OleDbCommand(strsql, objConnection)

首先，您在字段Style传递的值周围有方括号这不是一个有效的语法。 Jet引擎假定这是一个参数。实际上，传递参数是正确的方法。

a = "Select * from [" 
b = ComboBox1.Text
c = "] where Style = ?"
strsql = a & b & c
Dim objCommand As New OleDbCommand(strsql, objConnection)
objCommand.Parameters.AddWithValue("@p1", ComboBox2.Text)
Dim objDataAdapter As New OleDbDataAdapter(objCommand)
Dim objDataTable As New DataTable("Buyers")
objDataAdapter.Fill(objDataTable)

字段Style的值与参数一起传递。这留下了将占位符（？）替换为从组合框到框架的值的工作您可以确定它最好知道这样做可以避免错误和SQL注入。

此代码仍然很弱。您应该完全确定第一个combobox1的内容无法修改为包含恶意文本而不是表名

一次使用数据填充多个文本框

1 个答案: