Streamwriter 文件系统文本文件 vb.net

Question

我有一个带有复选框的数据网格，可以让用户进行多次删除。如何将删除的记录存储到逗号分隔的文本文件中？我正在使用 Access 来存储我的数据

我的删除代码是

Try
    con.Open()
    Sql = "DELETE FROM member WHERE ID = ?"

    With cmd
        .Connection = con
        .CommandText = Sql
        .Parameters.AddWithValue("@p1", 0)
    End With

    For Each row As DataGridViewRow In DataGridView1.Rows
        If row.Cells(0).FormattedValue = True Then
            cmd.Parameters("@p1").Value = Convert.ToInt32(row.Cells(1).FormattedValue)
            result = cmd.ExecuteNonQuery
        End If
    Next

    If result = 0 Then
        MsgBox("nothing.")
    Else
        MsgBox("deleted.")

    End If

Catch ex As Exception
    MsgBox(ex.Message)
End Try

con.Close()

Answer 1

在开始循环之前打开文件，使用 StreamWrite 传递所需的实际文件名 在每个循环中准备一个要写入文件的字符串。 （使用 string.Join 为从 gridview 获取的值创建一个逗号分隔的字符串

Using writer = new StreamWriter(.... your file name here ....)
Try
    con.Open()
    sql = "DELETE FROM member WHERE ID = ?"
    With cmd
        .Connection = con
        .CommandText = sql
        .Parameters.AddWithValue("@p1", 0)
    End With
    For Each row As DataGridViewRow In DataGridView1.Rows
       If row.Cells(0).FormattedValue = True Then
           ' Create a string from your current DataGridView,
           ' Note that I don't know in which columns are the data that
           ' that you want to save, so you need to adjust these readings
           Dim curText = string.Join(",", row.Cells(1).FormattedValue, _
                                          row.Cells(2).FormattedValue, _
                                          row.Cells(3).FormattedValue)


            cmd.Parameters("@p1").Value = Convert.ToInt32(row.Cells(1).FormattedValue)
            result = cmd.ExecuteNonQuery

            ' We delete one record for each loop, so we need to check the result for every
            ' loop. If we have a deleted record corresponding to ID passed then we can write
            ' the line that contains the data of the deleted record to the file
            If result > 0 Then
                writer.WriteLine(curText)
            End If
        End If
    Next
    .....

' The End Using closes the file and flushes everything to disk.
End Using

Answer 2

将记录信息存储到临时存储中，然后将其保存到文件中。

Dim deletedRecords As New List(Of String)
Try
    con.Open()
    For Each row As DataGridViewRow In DataGridView1.Rows
        If row.Cells(0).FormattedValue = True Then
         'concatenate the row data into a string
          deletedRecords.Add({this record data})
          sql = "DELETE FROM member WHERE id = '" _
          & CStr(row.Cells(1).FormattedValue) & "'"
          With cmd
                .Connection = con
                .CommandText = sql
          End With

          result = cmd.ExecuteNonQuery
        End If
    Next
    If result = 0 Then
        MsgBox("No Deleted Record.")
    Else
        MsgBox("The Record(s) has been deleted.")
    End If
Catch ex As Exception
    MsgBox(ex.Message)
End Try
con.Close()

'save to text file
Using sw As New StreamWriter({path})
  For Each delRec In deletedRecords
    sw.WriteLine(delRec)
  Next
End Using