如果不为空则更新文本框 [英] update textbox if not empty

问题描述

我想要将文本框的更新值更改为ms访问数据库，但我不想在文本框空白时进行任何操作



这个我的代码

  Dim  SavInto  As  新 OleDb.OleDbCommand 
  Dim  adapter2  As  新 OleDbDataAdapter（SQLstr，Conn）
 SavInto.Connection = Conn 
 SavInto.CommandType = CommandType.Text 
 SavInto.CommandText =   UPDATE Table1 SET Place ='&修剪（ComboBox2.SelectedItem）&  'WHERE FilNum ='& （TextBox1.Text）&  ' 
 SavInto.CommandText =   更新表1 SET Place ='&修剪（ComboBox2.SelectedItem）&  'WHERE FilNum ='& （TextBox2.Text）&  ' 
 SavInto.CommandText =   更新表1 SET Place ='&修剪（ComboBox2.SelectedItem）&  'WHERE FilNum ='& （TextBox3.Text）&  ' 
 SavInto.CommandText =   更新表1 SET Place ='&修剪（ComboBox2.SelectedItem）&  'WHERE FilNum ='& （TextBox4.Text）&  ' 
 SavInto.CommandText =   更新表1 SET Place ='&修剪（ComboBox2.SelectedItem）&  'WHERE FilNum ='& （TextBox5.Text）&  ' 
 SavInto.CommandText =   更新表1 SET Place ='&修剪（ComboBox2.SelectedItem）&  'WHERE FilNum ='& （TextBox6.Text）&  ' 
 SavInto.CommandText =   更新表1 SET Place ='&修剪（ComboBox2.SelectedItem）&  'WHERE FilNum ='& （TextBox7.Text）&  ' 
 SavInto.CommandText =   更新表1 SET Place ='&修剪（ComboBox2.SelectedItem）&  'WHERE FilNum ='& （TextBox8.Text）&  ' 
 Conn.Open（）
 SavInto.ExecuteNonQuery（）
 Conn.Close（）
 

i想要今天完成任何帮助吗？

解决方案

< blockquote>只需对文本框的内容进行测试即可包围CommandText位...

如果修剪（TextBox8.Text）。长度> 0然后
 SavInto.CommandText =UPDATE Table1 SET Place ='&修剪（ComboBox2.SelectedItem）& '在哪里FilNum ='& （TextBox8.Text）& '
结束如果

请注意，当你覆盖 SavInto.CommandText时，实际上只会执行你的最后一个命令每次。



最后，对SQL注入做一些研究，并用适当的参数替换字符串连接... http://msdn.microsoft.com/en-us/library/system.data.oledb.oledbcommand .parameters.aspx [ ^ ]

  Dim  tbList  As  StringBuilder = 新 StringBuilder（  （）' 比字符串连接更有效 
  For  每个 t  As  Control 在 我 .GroupBox1.Controls ' 我将所有相关的TextBox放入一个（不可见的）组框 
 如果  TypeOf （t）  TextBox 然后 
 如果修剪（t.Text）.Length>  0  然后 ' 仅对内容的文本框感兴趣
 tbList.Append（修剪（  '& t.Text）&  '，） 建立文本框内容列表 
 结束 如果 
 结束 如果 
 下一步 
 如果 tbList.Length>  1  然后 ' 有效检查所有空白框 
  Dim  cmdList  As  字符串 = tbList.ToString（）
 如果 cmdList.EndsWith（ ，）然后 cmdList = Strings.Left（cmdList， cmdList.Length  -   1 ）' 删除最后一个逗号 
 cmdList + =  ）  ' 将结束括号放在适当位置 
 SavInto.CommandText =   UPDATE Table1 SET Place =？在哪里FilNum& cmdList 
 SavInto.Parameters.Add（ComboBox2.SelectedItem）' 使用参数来避免SQL注入 
 Conn.Open（）
 SavInto.ExecuteNonQuery（）' 执行单个查询 
 Conn.Close（）
 结束 如果 

I want update value of textbox to ms access db but i dont want make any action if textbox left empty

this my code

Dim SavInto As New OleDb.OleDbCommand
     Dim adapter2 As New OleDbDataAdapter(SQLstr, Conn)
     SavInto.Connection = Conn
     SavInto.CommandType = CommandType.Text
     SavInto.CommandText = "UPDATE Table1 SET Place = '" & Trim(ComboBox2.SelectedItem) & "' WHERE FilNum ='" & (TextBox1.Text) & "'"
     SavInto.CommandText = "UPDATE Table1 SET Place = '" & Trim(ComboBox2.SelectedItem) & "' WHERE FilNum ='" & (TextBox2.Text) & "'"
     SavInto.CommandText = "UPDATE Table1 SET Place = '" & Trim(ComboBox2.SelectedItem) & "' WHERE FilNum ='" & (TextBox3.Text) & "'"
     SavInto.CommandText = "UPDATE Table1 SET Place = '" & Trim(ComboBox2.SelectedItem) & "' WHERE FilNum ='" & (TextBox4.Text) & "'"
     SavInto.CommandText = "UPDATE Table1 SET Place = '" & Trim(ComboBox2.SelectedItem) & "' WHERE FilNum ='" & (TextBox5.Text) & "'"
     SavInto.CommandText = "UPDATE Table1 SET Place = '" & Trim(ComboBox2.SelectedItem) & "' WHERE FilNum ='" & (TextBox6.Text) & "'"
     SavInto.CommandText = "UPDATE Table1 SET Place = '" & Trim(ComboBox2.SelectedItem) & "' WHERE FilNum ='" & (TextBox7.Text) & "'"
     SavInto.CommandText = "UPDATE Table1 SET Place = '" & Trim(ComboBox2.SelectedItem) & "' WHERE FilNum ='" & (TextBox8.Text) & "'"
     Conn.Open()
     SavInto.ExecuteNonQuery()
     Conn.Close()

i want finish it today maximum any help?

解决方案

Just surround the CommandText bits with a test on the contents of the text box ...

If Trim(TextBox8.Text).Length > 0 Then
     SavInto.CommandText = "UPDATE Table1 SET Place = '" & Trim(ComboBox2.SelectedItem) & "' WHERE FilNum ='" & (TextBox8.Text) & "'"
End If

Note that only your last command will actually be executed as you're overwriting SavInto.CommandText each time.

Finally, do some research on SQL Injection and replace the string concatenation with proper parameters ... http://msdn.microsoft.com/en-us/library/system.data.oledb.oledbcommand.parameters.aspx[^]

[Edit - an alternative approach that is extensible, avoids SQL injection and uses a single update statement]

Dim tbList As StringBuilder = New StringBuilder("(")    'More efficient than string concatenation
        For Each t As Control In Me.GroupBox1.Controls          'I placed all the relevent TextBoxes into an (invisible) group box
            If TypeOf (t) Is TextBox Then
                If Trim(t.Text).Length > 0 Then                 'Only interested in textboxes with content
                    tbList.Append(Trim("'" & t.Text) & "',")    'Build up a list of the textbox contents
                End If
            End If
        Next
        If tbList.Length > 1 Then   'Effectively checks for all boxes being empty
            Dim cmdList As String = tbList.ToString()
            If cmdList.EndsWith(",") Then cmdList = Strings.Left(cmdList, cmdList.Length - 1) 'Remove last comma
            cmdList += ")"          'Put the closing bracket in place
            SavInto.CommandText = "UPDATE Table1 SET Place = ? WHERE FilNum in " & cmdList
            SavInto.Parameters.Add(ComboBox2.SelectedItem)  'Use parameters to avoid SQL Injection
            Conn.Open()
            SavInto.ExecuteNonQuery()       'Execute the single query
            Conn.Close()
        End If

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