从 MS Access 2007 DB (VB.net) 下载文件

Question

您好，我正在使用 VB.net 创建一个 Windows 应用程序，我想知道如何创建一个下载按钮，以便当用户单击它时，它能够从数据库中的附件列下载特定附件。

我试图用谷歌搜索如何去做这件事，但不幸的是，我仍然找不到答案。如果有这方面经验的人能够指导我编写此函数的过程，我将不胜感激。

Answer 1

使用 DAO（添加 Microsoft.Office.Interop.Access.Dao.DLL 的引用）从 Ms-Access 数据库读取附件字段。

示例代码：

Imports Microsoft.Office.Interop.Access
Public Class Form1
   Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        Dim FileName = "c:\WindowsApplication1\Database1.accdb"

        'Directory location where attachment files will be stored.
        Dim Path = "c:\WindowsApplication1\"

        Dim engine As New Dao.DBEngine
        Dim database As Dao.Database = engine.OpenDatabase(FileName)

        Dim rs As Dao.Recordset = database.OpenRecordset("select MyAttachmentField from  TableName")
        While Not rs.EOF
            Dim rs1 As Dao.Recordset2 = rs.Fields("MyAttachmentField").Value
            While Not rs1.EOF
                Dim fName As String = Path & rs1("FileName").Value
                Dim fld As Dao.Field2 = rs1("FileData")
                'Delete a file if same named file exists
                System.IO.File.Delete(fName)
                fld.SaveToFile(fName)
                rs1.MoveNext()
            End While
         rs.MoveNext()
        End While
    End Sub
End Class