将数据从数据表导出到文本。 VB.NET [英] Exporting data from data table to text. VB.NET

问题描述

我正在创建一个用于群发电子邮件的Windows窗体应用程序。我的联系人数据存储在数据表Customer中。现在我想将我的客户数据导出到文本文件。我有我的代码，但我一直想出一个空文件。我调试了代码并看到
它实际上正在读取数据，但它没有写入文本文件。以下是我的代码。有人可以告诉我我做错了吗？

 Dim ds As DataSet = MassEMailDataSet（）
 Dim dt As DataTable = ds.Tables （" Customer"）
 Dim filename As String =" C：\\\\\\\\\\\\\\\ 
 Dim sepChar As String ="，" 
 Dim writer As StreamWriter 
 
 writer = New StreamWriter（filename）
 
 Dim sep As String ="" 
 Dim builder As New Text.StringBuilder 
 
'标题行
 For each col As DataColumn in dt.Columns 
 builder.Append（sep）.Append（col。 ColumnName）
 sep = sepChar 
下一个
 writer.WriteLine（builder.ToString（））
 
'行行
 For Each row As DataRow in dt .Rows 
 sep ="" 
 For each col As DataColumn in dt.Columns 
 builder.Append（sep）.Append（row（col.ColumnName））
 sep = sepChar 
 Next 
 writer .WriteLine（builder.ToString（））
 builder.Clear（）
 Next 
 MsgBox（" Export done！"）

解决方案

嗨朋友，

很抱歉我迟到的回复。

我无法测试你的代码，因为项目中有一些未知变量，如果你想将数据中的数据导出到文本，我建议你可以参考下面这个成功的演示，在这个演示中，我在我的代码中模拟一个数据表。

 Imports System.IO 
 Imports System.Text 
 
 Public Class Form2 
 Private Sub Button1_Click（sender As Object，e As EventArgs）Handles Button1.Click 
 Dim T_Ge nder As New DataTable（）
 T_Gender.Columns.AddRange（New DataColumn（）{New DataColumn（" GenderID"），New DataColumn（" GenderName"）}）
 
 T_Gender。 Rows.Add（New Object（）{" 1"，"Man"}）
 T_Gender.Rows.Add（New Object（）{" 2"，" Female"}）
 T_Gender.Rows.Add（New Object（）{" 3"，" Secret"}）
 
 Dim filename As String =" D：\\\\\\\\\\\\\ 
 
 Dim _nRowIndex As Integer = 1 
使用_objWriter作为新StreamWriter（filename，False，Encoding.UTF8）
 For Each row As DataRow In T_Gender.Rows 
 _nRowIndex + = 1 
 For Each col As DataColumn In T_Gender.Columns 
 _objWriter.WriteLine（row（col.ColumnName）.ToString（））
 Next 
 Next 
 End使用
结束子
结束类

¥b $ b

希望这有帮助！

最好的问候，

Stanly

I am creating a windows forms application for mass e-mailing. My contact data is stored in a data table Customer. Now I want to export my Customer data to a text file. I have my code but I keep coming up with an empty file. I debugged the code and saw that it is actually reading the data but it's not written to the text file. Below is my code. Can someone please tell me what I am doing wrong?

            Dim ds As DataSet = MassEMailDataSet()
            Dim dt As DataTable = ds.Tables("Customer")
            Dim filename As String = "C:\EMail\ExportTest.txt"
            Dim sepChar As String = ","
            Dim writer As StreamWriter

            writer = New StreamWriter(filename)

            Dim sep As String = ""
            Dim builder As New Text.StringBuilder

            'header line
            For Each col As DataColumn In dt.Columns
                builder.Append(sep).Append(col.ColumnName)
                sep = sepChar
            Next
            writer.WriteLine(builder.ToString())

            'row lines
            For Each row As DataRow In dt.Rows
                sep = ""
                For Each col As DataColumn In dt.Columns
                    builder.Append(sep).Append(row(col.ColumnName))
                    sep = sepChar
                Next
                writer.WriteLine(builder.ToString())
                builder.Clear()
            Next
            MsgBox("Export done!")

解决方案

Hi friend,

Sorry for my late reply.

I can not test your code because there are some unknown variable in your project, and if you want to export the data within datatable to text, I suggest you can refer to the following successful demo, in this demo, I simulate a datatable in my code.

Imports System.IO
Imports System.Text

Public Class Form2
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim T_Gender As New DataTable()
        T_Gender.Columns.AddRange(New DataColumn() {New DataColumn("GenderID"), New DataColumn("GenderName")})

        T_Gender.Rows.Add(New Object() {"1", "Man"})
        T_Gender.Rows.Add(New Object() {"2", "Female"})
        T_Gender.Rows.Add(New Object() {"3", "Secret"})

        Dim filename As String = "D:\Log\ExportTest.txt"

        Dim _nRowIndex As Integer = 1
        Using _objWriter As New StreamWriter(filename, False, Encoding.UTF8)
            For Each row As DataRow In T_Gender.Rows
                _nRowIndex += 1
                For Each col As DataColumn In T_Gender.Columns
                    _objWriter.WriteLine(row(col.ColumnName).ToString())
                Next
            Next
        End Using
    End Sub
End Class

Hope this helps!

Best Regards,

Stanly

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