如何在每行末尾添加文本vb.net

Question

I'm developing a program with VB.NET (2013), which works with a local database (sql server 2008 R2), The program is converting database tables into text files , so how to add some text after the last field of each row at the end of each line in that text file, Thanks, And sorry for my english

If mytable.HasRows Then
                Dim outputStream As StreamWriter = New StreamWriter(FileName & "table.txt", True, GetEncoding)
                Dim row As Integer = 0
                myConnection.open()
                Do While mytable.Read                    
                    Dim header As Integer = 0
                    Dim counter As Integer = 0
                    Dim fieldCount As Integer = mytable.FieldCount - 1

                    While counter <= fieldCount
                        If counter = 0 Then
                            outputStream.Write("None ," )
                        End If
                        If counter = 3 Then
                            outputStream.Write("123456 ," )
                        End If
                        If counter = 7 Then
                            outputStream.Write("None ," )
                        End If

                        If counter <> fieldCount Then
                            outputStream.Write(mytable(counter).ToString() & ",")
                        Else
                            outputStream.WriteLine(mytable(counter).ToString())
                        End If
                        counter += 1
                    End While
                    row += 1

                Loop
                mytable.Close()
                outputStream.Close()
                myConnection.Close()
            End If

Answer 1

Using the example you have provided, you could replace

                    If counter <> fieldCount Then
                        outputStream.Write(mytable(counter).ToString() & ",")
                    Else
                        outputStream.WriteLine(mytable(counter).ToString())
                    End If

With:

                    If counter <> fieldCount Then
                        outputStream.Write(mytable(counter).ToString() & ",")
                    Else
                        outputStream.WriteLine(mytable(counter).ToString() & "What ever you want to write")
                    End If

Answer 2

Here's a refactor of the code with your question answered:

Imports System.Data.SqlClient
Imports System.Data
Public Class Class1
    Public Sub Writefile()
        Dim ConnectionString As String = ""
        Using cnn As New SqlConnection(ConnectionString)
            cnn.Open()
            Using cmd As SqlCommand = cnn.CreateCommand
                cmd.CommandType = System.Data.CommandType.Text
                cmd.CommandText = "SELECT * FROM SomeTable"
                Using da As New SqlDataAdapter
                    Using ds As New DataSet
                        da.Fill(ds)
                        Using sw As New System.IO.StreamWriter("C:\myfile.txt")
                            For Each r As DataRow In ds.Tables(0).Rows
                                Dim output As New System.Text.StringBuilder
                                For c As Integer = 0 To ds.Tables(0).Columns.Count - 1
                                    Select Case c
                                        Case 0
                                            output.Append("none ,")
                                        Case 3
                                            output.Append("123456 ,")
                                        Case 7
                                            output.Append("none ,")
                                        Case Else
                                            output.Append(r(c).ToString)
                                            If c < ds.Tables(0).Columns.Count - 1 Then
                                                output.Append(",")
                                            End If
                                    End Select
                                    sw.WriteLine(output.ToString)
                                Next
                            Next
                        End Using
                    End Using
                End Using
            End Using
        End Using
    End Sub
End Class

This sample includes the database call as well. The "Using" blocks will ensure that your objects are disposed and closed appropriately, as well. I use this pattern and patterns like it all the time for writing text files.