级联选择列表 [英] Cascading Pick Lists

问题描述

我对Cascading DropDown列表有一点问题，我希望它只是那个 我不明白Lightswitch的概念，或者我错误地设计了数据库，以便LightSwitch有效使用。

我有4张桌子。

1 - 部门，2 - 子部门，3 - 教师，4 - TeacherstoDepartmentsMapping（pkid，departmentid，teacherid）

我有1个屏幕，您首先选择部门，然后第二个DDL填充所选部门的所有子部门。有一个很棒的帖子，我的工作正常。 （ http://blogs.msdn.com/b/lightswitch/archive/2010/11/15/how-to-use-lookup-tables-with-parameterized-queries-karol-zadora-przylecki.aspx ）

我无法工作的是第三个DDL，它应该显示所有教授所选部门的教师。我在Mapping表中创建了一个关系到教师表的关系。该工作正常。

我试图完成这两种方式，但似乎都不起作用：

1）我在映射表上创建了一个查询，但是当我将查询添加到屏幕并将参数映射到屏幕时，它没有显示为"选择"。对于教师下拉列表。 （我假设这是因为查询引用的基表是不同的？）

2）我在教师表上创建了一个查询，但是我没有看到任何对该表的引用映射表在查询屏幕的过滤器部分，所以我无法创建参数化过滤器。我想也许我可以使用"预处理查询"引用不在过滤器列表中的字段
，但我不知道它是如何工作的。

我希望这是有意义的

<非常感谢你的帮助！

Scott

解决方案

嗨  Scott

问题：教师可以在多个子部门吗？

 

Jaime

I'm having a little problem with Cascading DropDown lists and I'm hoping it's just that I don't understand the concepts of Lightswitch or I've designed the DB incorrectly for LightSwitch to use effectively.

I have 4 tables.

1 - Departments, 2 - SubDepartments, 3 - Teachers, 4 - TeacherstoDepartmentsMapping(pkid, departmentid, teacherid)

I have 1 screen where you select the department first, then the second DDL populates with all the subdepartments that are a part of the selected department. I have that working fine thanks to a great post. (http://blogs.msdn.com/b/lightswitch/archive/2010/11/15/how-to-use-lookup-tables-with-parameterized-queries-karol-zadora-przylecki.aspx)

What I can't get working is the 3rd DDL which should show all the teachers that teach for the selected department. I created a relationship in the Mapping table to the teachers table which works fine.

I tried to accomplish this 2 ways, but neither seem to work:

1) I created a query on the mapping table, but when I add the query to the screen, and map the parameter to the screen, it doesn't show as a "Choice" for the Teacher drop down list. (I assume this is becuase the base table referenced by the query is different?)

2) I created a query on the teachers table, but I don't see any reference to the mapping table in filter section of the Query screen, so I can't create a parameterized filter. I was thinking maybe I could use "Preprocess Query" to reference fields that aren't in the filter list, but I have no idea how that works.

I hope that makes sense

Thank you very much for your help!

Scott

解决方案

Hi Scott

Question: can a teacher be in more than one sub-department?

 

Jaime

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