将数值从文本框更新为db [英] update numeric value from textbox to db

问题描述

我已经坚持了一段时间..

i've been stuck with it for a while..

我的db（sqlite）值设置为double。当我尝试从文本框更新（每个keydown更新数据库）我每次删除一个值时出现一堆错误，文本框是空白的，当我偶然键入一个字符或尝试使用减号" - " ;。

my db (sqlite) value is set to double. when i try to update from a textbox (each keydown updates the db) i get bunch of errors every time i delete a value and the textbox is blank, when i type a charecter by accident or try to use the minus sign "-".

实际上，如果我在输入一个数字后使用它而不是之前使用减号它会起作用.. 

actually, with the minus sign it works if i use it after entering a number and not before.. 

我理解db不能接受非数字字符的逻辑，但我不能强迫它只提供数字，减号或保持空白..

i understand the logic that the db cant accept non-numeric characters but i can't force it to reffer only to numbers ,minus sign or keep it blank..

帮助任何人吗？

推荐答案

你好noampro8

Hi noampro8

这样做

  Private Sub TextBox_KeyDown(Sender As Object, e As KeyEventArgs) Handles TextBox.KeyDown
    Try
      If e.KeyCode = Keys.Enter Then
        If String.IsNullOrEmpty(Sender.Text) = False AndAlso
          Microsoft.VisualBasic.IsNumeric(Sender.Text) Then
          'Do Update
          e.SuppressKeyPress = True
        Else
          System.Windows.Forms.SendKeys.Send("{TAB}")
          e.SuppressKeyPress = True
        End If
      End If
    Catch ex As Exception
      System.Windows.Forms.MessageBox.Show(ex.Message, "Error", System.Windows.Forms.MessageBoxButtons.OK, System.Windows.Forms.MessageBoxIcon.Error)
    End Try
  End Sub

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