这段代码究竟做了什么？ [英] What does this code do exactly?

问题描述

受保护的子Button1_Click（发件人为对象，e为EventArgs）处理Button1.Click





Dim conn As New OleDbConnection（ Provider = Microsoft.ACE.OLEDB.12.0; Data Source = C：\ Users \Draus \Documents\Visual Studio 2012 \WebSites\sampledb\Database5.accdb;）





Dim cmd当OleDbCommand =新OleDbCommand（SELECT F_Name FROM [Bowlers]，conn）







conn.Open（）

Dim读取为OleDbDataReader = cmd.ExecuteReader（）

如果read.HasRows然后

当read.Read（）

Dim Fname As String = read.Item（F_Name）

结束时

结束如果



结束Sub

Protected Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click


Dim conn As New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\Draus\Documents\Visual Studio 2012\WebSites\sampledb\Database5.accdb;")


Dim cmd As OleDbCommand = New OleDbCommand("SELECT F_Name FROM [Bowlers]", conn)



conn.Open()
Dim read As OleDbDataReader = cmd.ExecuteReader()
If read.HasRows Then
While read.Read()
Dim Fname As String = read.Item("F_Name")
End While
End If

End Sub

推荐答案

它连接到ms访问数据库，从Bowlers表中检索F_name列数据，然后遍历i t使用读取器将数据存储在名为FName的变量中。奇怪的是，它似乎没有对var做任何事情，也没有返回它。除非我遗漏了什么，否则它不会做任何永久性的事情。即使它对FName变量做了某些事情，它也只有数据集中最后一行的值。

It connects to a ms access database, retrieves the F_name column data from the Bowlers table and then iterates through it with a reader storing the data in a variable named FName. Strangely, it doesn't seem to do anything with the var, nor return it. Unless I am missing something it isn't doing anything permanent. Even if it did something with the FName variable, it would only have the value of the last row in the dataset.

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