问题描述
提前抱歉我的无知。任何帮助肯定会赞赏
。我正在用VB.Net写一个相当简单的应用程序和
显然是一个新手。此应用程序将由1,2和/或
或最多3人同时使用，我正在使用Access 2003获取我的数据
来源。我们没有处理大量的数据（5或6
表，总共可能有3,000条记录 - 一张表格中的大部分是
）。这个应用程序使用一个相当简单的形式，
但是在离开某些文本框时，我想填写一些数据。对于
实例，我可能有一个竞赛号码字段 -
当我离开它时，我想填写一个描述。下一个字段
可能是竞争对手的号码，当我离开时，我想用竞争对手的名字填充一个
字段。
足够的背景 - 我创建了一个模块来打开我的连接
以及其中的一个函数来处理我的DataReader。在那个模块中我
有：
Imports System.Data
Imports System.data.oledb
Imports System.Data.sqlclient
Module Main
Public strConn As String =" Provider = Microsoft.Jet.OLEDB.4.0;数据
源= f：\ mydatabase.mdb"
Public cn As New OleDbConnection（strConn）
函数ExecuteReader（ ByVal sSQLString As String）As
OleDb.OleDbDataReader
Dim dr As OleDbDataReader
Dim cmd As OleDbCommand = New OleDbCommand（sSQLString ，cn）
尝试
如果cn.State = ConnectionState.Closed那么cn.Open（）
dr = cmd.ExecuteReader（）
cmd.Dispose（）
Catch ex As OleDbException
MsgBox（ex.Message，MsgBoxStyle.Exclamation）
结束尝试
返回博士
结束功能
结束模块
那个到目前为止，它几乎就是这样。在我的主要代码中，我有：
Private Sub txtCompNum_Leave（ByVal sender As Object，ByVal e As
System.EventArgs）处理txtCompNum.LostFocus
Dim dr As OleDbDataReader
dr = ExecuteReader（" SELECT * FROM competition where compnum =
"&"''"& txtCompNum.Text&"''"）
当dr.Read
txtDance.Text = dr.GetString（2）
结束时
dr.Close（）
End Sub
Private Sub txtCompetitor_Leave（ByVal sender As Object，ByVal e As
System.EventArgs）处理txtCompetitor.Leave
Dim dr As OleDbDataReader
dr = ExecuteReader（" SELECT * FROM dancer where cardnum =" &
txtCompetitor.Text）
当dr.Read
txtName.Text = dr.GetString（3）& ， &安培; dr.GetString（4）
结束时
dr.Close（）
cn.Close（）
结束子
这些似乎工作得很好而且速度很快。但是有一些问题：
1.是否有正确的问题。结构创建不同的
组件填充表单所需的组件，如果是这样，到目前为止我的
右行是什么？
2.我应该使用离开吗？或Lost_Focus或Lost_Focus。对于我的文本框？我以前用
使用Lost_Focus使用VB6，但想知道是否有差异
或者如果首选。
3.如果上面的两个数据站只返回一条记录，则是还有一些
其他读者我应该用它来提高性能吗？
任何其他建议一定会受到赞赏。我有点
湿漉漉的耳朵所以我会喜欢一些帮助。
谢谢！
Steve
Sorry in advance for my ignorance. Any help would sure be
appreciated. I''m writing a fairly simple application with VB.Net and
am obviously a bit of a newbie. This application will be used by 1, 2
or at most 3 people concurrently and I''m using Access 2003 for my data
source. We are not dealing with a large amount of data (5 or 6
tables, for a total of maybe 3,000 records - one table having the
majority of that). This application is using a fairly simple form,
but upon leaving certain text boxes, I want to fill in some data. For
instance, I might have one field that is for a competition number -
when I leave it, I want to populate a description. The next field
might be a competitor number and when I leave it, I want to populate a
field with the competitor name.
Enough of the background - I created a module to open my connection
and a function within that to handle my DataReader. In that module I
have:
Imports System.Data
Imports System.data.oledb
Imports System.Data.sqlclient
Module Main
Public strConn As String = "Provider=Microsoft.Jet.OLEDB.4.0; Data
Source=f:\mydatabase.mdb"
Public cn As New OleDbConnection(strConn)
Function ExecuteReader(ByVal sSQLString As String) As
OleDb.OleDbDataReader
Dim dr As OleDbDataReader
Dim cmd As OleDbCommand = New OleDbCommand(sSQLString, cn)
Try
If cn.State = ConnectionState.Closed Then cn.Open()
dr = cmd.ExecuteReader()
cmd.Dispose()
Catch ex As OleDbException
MsgBox(ex.Message, MsgBoxStyle.Exclamation)
End Try
Return dr
End Function
End Module
And that''s pretty much it so far. In my main code I have:
Private Sub txtCompNum_Leave(ByVal sender As Object, ByVal e As
System.EventArgs) Handles txtCompNum.LostFocus
Dim dr As OleDbDataReader
dr = ExecuteReader("SELECT * FROM competition where compnum =
" & "''" & txtCompNum.Text & "''")
While dr.Read
txtDance.Text = dr.GetString(2)
End While
dr.Close()
End Sub
Private Sub txtCompetitor_Leave(ByVal sender As Object, ByVal e As
System.EventArgs) Handles txtCompetitor.Leave
Dim dr As OleDbDataReader
dr = ExecuteReader("SELECT * FROM dancer where cardnum = " &
txtCompetitor.Text)
While dr.Read
txtName.Text = dr.GetString(3) & ", " & dr.GetString(4)
End While
dr.Close()
cn.Close()
End Sub
These seem to work well and fast. But there are a few questions:
1. Is there a "right" way to structure creating the different
components necessary to populate my form and if so, is mine along the
right lines so far?
2. Should I use "Leave" or "Lost_Focus" for my text boxes? I used to
use "Lost_Focus" with VB6, but was wondering if there was a difference
or if one was preferred.
3. If the two datareaders above only return one record, is there some
other reader I should use to improve performance?
Any other suggestions would sure be appreciated. I''m a bit
wet-behind-the-ears so I''d love some help.
Thanks!
Steve
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