VB.NET来自2个表的数据绑定 [英] VB.NET Databinding from 2 Tables

问题描述

我具有以下结构

|-Table 1
|--PK IDT1
|--Name field
|-Table 2
|--PK ID
|--FK IDT1
|--Name field

我想将表1绑定到combobox1，将表2绑定到combobox2，这样当有人在combobox1中选择一个值时，combobox2仅填充FK中的行来自combobox1的IDT1值。

I want to bind Table 1 to combobox1 and Table 2 to combobox2 so as when someone selects a value in combobox1, combobox2 populates with only the rows with the FK IDT1 value from combobox1. Is this possible with databinding or do I have to code it?

推荐答案

在 FORM_LOAD 仅填充 ComboBox1 。此伪代码可能会帮助您：

on the FORM_LOAD of your application just populate only ComboBox1. this psuedocode may help you:

在您的应用程序上进行表单加载：

ON FORM_LOAD of your Application:

      Bind ComboBox1
      SET DISPLAY MEMBER Property of BomboBox1 to field
      SET VALUE MEMBER Property of ComboBox1 to IDT1
      Clear ComboBox1 current Text

在 ComboBox1

      Bind ComboBox2 using the following Query:
           SELECT ID, field FROM Table2 WHERE IDT1 = ComboBox1.SelectedValue.ToString
      SET DISPLAY MEMBER Property of ComboBox2 to field
      SET VALUE MEMBER Property of ComboBox2 to IDT

SelectedIndexChanged 每次SelectedIndex属性值更改时，都会引发事件。如果您的ComboBox最初为空，则其SelectedIndex为-1。当您将数据绑定到它时，默认情况下会选择第一项，并且SelectedIndex更改为0。然后，您再次将SelectedIndex显式设置为-1。

The SelectedIndexChanged event is raised every time the SelectedIndex property value changes. If your ComboBox is initially empty then its SelectedIndex is -1. When you bind data to it the first item is selected by default and the SelectedIndex changes to 0. You are then explicitly setting the SelectedIndex to -1 again.

仅对知道用户何时进行选择然后处理 SelectionChangeCommitted 事件感兴趣。

If you're only interested in knowing when the user makes a selection then handle the SelectionChangeCommitted event instead.

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