如何设置允许的十进制值？

Question

基本上，我在数据库中插入了一个值，其中的值可以是十进制的任何值，但是我想阻止用户输入不以.50或.00结尾的任何值（例如，如果Qtytxt1.text =“ 2.34”则错误），但如果以.50或.00结尾，那么它将允许我插入（例如，如果Qtytxt1.text =“ 2.50”然后插入），这是一个代码段：

If Qtytxt1.Text <> "" And Qtytxt1.Text <> "0" And Count = 1 Then
                            command = New SqlCommand("INSERT INTO GRN([POD Id], [Delivered     Qty], [Delivered Date], [Delivery No], [User]) " & _
                                              "VALUES ('" + PodId.Value + "','" + Qtytxt1.Text + "','" + ReceivedDate1.Text + "','" + DeliveryNo1.Text + "','" + Uname.ToString + "')", connection)
                            command.ExecuteNonQuery()
 End If
                    Else
                        Messagebox.Show("Cannot Save, Need To Fill The Received Date , Delivery No Or Qty exceedes the Bal...!")
                        Exit For
                    End If
crow = crow + 1
            End If
        Catch ex As Exception
            Messagebox.Show("Error in Inserting the Value in GRN Table....!")
            Exit Sub
        Finally
            connection.Close()
        End Try
    Next
    If crow >= 1 Then
        Messagebox.Show("GRN has been updated successfully")
        save = True
    End If

所以我知道应该是这样的：

 If Qtytxt1.Text <> "" And Qtytxt1.Text <> "0" And Count = 1 Then
 If Qtytxt1.Text Ends in .50 or .00 Then 
  Messagebox.Show("Please check Delivered Quantity ends in .50 or .00!") 
 Exit Sub
                        Else    command = New SqlCommand("INSERT INTO GRN([POD Id], [Delivered     Qty], [Delivered Date], [Delivery No], [User]) " & _
                                              "VALUES ('" + PodId.Value + "','" + Qtytxt1.Text + "','" + ReceivedDate1.Text + "','" + DeliveryNo1.Text + "','" + Uname.ToString + "')", connection)
                            command.ExecuteNonQuery()
 End If
 End If
                    Else
                        Messagebox.Show("Cannot Save, Need To Fill The Received Date , Delivery No Or Qty exceedes the Bal...!")
                        Exit For
                    End If
crow = crow + 1
            End If
        Catch ex As Exception
            Messagebox.Show("Error in Inserting the Value in GRN Table....!")
            Exit Sub
        Finally
            connection.Close()
        End Try
    Next
    If crow >= 1 Then
        Messagebox.Show("GRN has been updated successfully")
        save = True
    End If

Answer 1

我将其放在您的TextBox的textChanged事件中。 我不确定您是否使用了“提交”按钮或其他功能，但这只是验证输入的内容是数字（即只有一个小数点，没有字母），并且可以被.50整除。

If IsNumeric(Qtytxt1.text) AndAlso CDec(Qtytxt1.Text) Mod .50 = 0 Then
    Me.btnSubmit.Enabled = True
Else
    Me.btnSubmit.Enabled = False
End If

另外，您应该按照SLak的建议查看SQL Injection漏洞。 使用参数会更好。