为什么不能将条件查询的条件指定为表单组件? [英] Why can't I specify criteria for a conditional query as a form component?

问题描述

我有两个下拉菜单，Combo_A和Combo_B. 我正在尝试实现级联组合框"或同步组合框"，其中从组合A(例如，美国州)中选择的内容将填充到组合B(例如，属于该州的特定城市列表). /p>

我了解使用VBA代码执行此操作，以及您希望使用VBA的原因，但我的问题是为什么必须使用VBA.

只需执行以下条件的条件查询:

[表格]！[主表格]！[状态下拉]

似乎不起作用. 在(State_Dropdown的)更新后执行了(City_Dropdown的)重新查询. 然后要求我提供

的值

Form!Main_Form!State_Dropdown

...在操作了State_Dropdown之后.

为什么这不直观? 安全? 功能吗?

解决方案

假定控件使用相同的表单，则无需引用Forms集合和表单名称.在ComboB RowSource中:
SELECT [City] FROM [Cities] WHERE [State]=[ComboA];

我建议重新查询代码在ComboB GotFocus事件中.

请注意，如果ComboB RowSource包含查找别名，则级联组合框不适用于连续表单或数据表表单.

I have two drop downs, Combo_A and Combo_B. I'm attempting to achieve a "cascading combo box" or "synchronous combo box" where a selection from Combo A (say, a US State) would populate Combo B (say a particular list of cities which belong to said state).

I understand using the VBA code to do this, and the reason you'd prefer to use VBA, but my question is WHY must I use VBA.

Simply making a conditional query with criteria of:

[Forms]![Main_Form]![State_Dropdown]

Doesn't seem to work. There IS a requery (of the City_Dropdown) performed AfterUpdate (of the State_Dropdown). Then I'm asked to provide the values for

Form!Main_Form!State_Dropdown

...after manipulating the State_Dropdown.

Why doesn't this work intuitively? Security? Function?

解决方案

Assuming the controls are on same form, don't need to reference the Forms collection and form name. In ComboB RowSource:
SELECT [City] FROM [Cities] WHERE [State]=[ComboA];

I recommend the requery code be in ComboB GotFocus event.

Be aware cascading comboboxes don't work nice with continuous or datasheet form if ComboB RowSource includes lookup alias.

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