如何从组合框参数化查询? [英] how to parameterized query from combo box?

问题描述

我有2个组合框:

第一个组合框将显示老师的姓名，第二个组合框将显示该老师所教的所有主题，我的问题是我不知道如何使用ado.net(VB.NET)对其进行编程，请帮助我在编码这种情况下:)

它适用于Windows，请给我一些有关它的示例代码
感谢

Hi I have 2 combo-box :

1st combobox will show the teacher''s name and the 2nd combo box will show all the subject that this particular teacher teach ,my problem is I don''t know how to program it using ado.net (VB.NET) please help me in coding this scenario :)

Its for windows and please give me some sample code about it
thanks

推荐答案

您正在寻找的功能称为层叠下拉菜单

将CascadingDropDown与数据库一起使用 [

The functionality you are looking for is called cascading dropdown

Using CascadingDropDown with a Database[^]

You didn''t specify if this were Web or Windows but the technique is the same, just applied differently in each.

双击要查询的combox....并用连接来写查询，并在查询中写--WHERE field =& ComboBox1.text&" ....


尝试此操作，您将得到答案....

double click on combox on which you want to query .... and there write querty with with connection and in query write like -- WHERE field=" & ComboBox1.text & "....


try this u wil get the thing....

实际上，MSDN在ADO.NET上有很多文章，它们可以为您提供的信息比这里的任何人都能得到的答案还多.
因此，我建议您从那里开始阅读，如果遇到某个主题或一段代码，请回到这里.
ADO.NET概述 [ IDbCommand(所有DbCommand对象的基本接口) [ DbCommand(IDbCommand的基本实现) [ OleDbCommand(IDbCommand的实现，继承自DbCommand) [ ^ ]
SqlCommand(使用SQL时使用的命令) [ ^ ]

对于参数化查询:
IDbDataParameter的衍生物 [ IDbConnection的衍生物 [ IDataAdapter的衍生物 [完整的代码示例 [可理解的方法:在TreeView中显示分层数据(例如，教师-班级) [ ^ ]

给一个人一条鱼，他会吃一天，教他如何钓鱼，他会一辈子吃东西(或其他).
祝你好运！ :)

Actually MSDN has quite some articles on ADO.NET which can tell you more than anyone here could fit it an answer.
So I suggest you start reading there and come back here if you get stuck on a subject or piece of code.
ADO.NET Overview[^]

Command Object, for executing queries:
IDbCommand (the base Interface for all DbCommand Objects)[^]
DbCommand (basic Implementation of IDbCommand)[^]
OleDbCommand (an Implementation of IDbCommand, Inherits from DbCommand)[^]
SqlCommand (Command to use when working with SQL)[^]

For parameterized queries:
Derivatives of IDbDataParameter[^]

Other Objects you will need:
Derivatives of IDbConnection[^]
Derivatives of IDataAdapter[^]

How to''s:
Complete code samples[^]
Walkthough: Displaying hierarchical data in a TreeView (for example teacher - classes)[^]

Give a man a fish and he will eat for a day, teach him how to fish and he will eat for a lifetime (or something).
Good luck! :)

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