使用 VB.Net 从 Access 数据库下载文件到本地 PC

如何解决使用 VB.Net 从 Access 数据库下载文件到本地 PC

Imports System
Imports System.IO
Imports System.Text
Imports System.Data.OleDb

Public Class VirtualStorage

    Dim conn As New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + Application.StartupPath + "\\Safevault.accdb")


    Dim dr,dr2 As OleDbDataReader



    Private Sub btnbrow_Click(sender As Object,e As EventArgs) Handles btnbrow.Click
        Dim OFP As New OpenFileDialog

        OFP.Filter = "All files (*.*)|*.*|txt files (*.txt)|*.txt"

        OFP.ShowDialog()

        txtfilepath.Text = OFP.FileName



    End Sub

      
    Private Sub ReadData()
        Dim cmd As New OleDbCommand("SELECT * FROM filestorage WHERE username = @id",conn)
        cmd.Parameters.Add("@id",OleDbType.VarChar).Value = x
        conn.open()
        dr = cmd.ExecuteReader
        While dr.Read
            DGVSV.Rows.Add(dr.Item("id").ToString,dr.Item("filename").ToString,dr.Item("filedata"))
        End While
        conn.Close()
    End Sub

    Private Sub btndownload_Click(sender As Object,e As EventArgs) Handles btndownload.Click
        DownloadData()
    End Sub

    Private Sub DownloadData()
        Dim cmd2 As New OleDbCommand("SELECT * FROM filestorage WHERE ID = @id",conn)
        Dim i,j As Integer
        i = DGVSV.CurrentRow.Index
        cmd2.Parameters.Add("@id",OleDbType.VarChar).Value = DGVSV.Item(0,i).Value

        conn.open()

        dr2 = cmd2.ExecuteReader

        While dr2.Read

            Dim fileBytes As Byte() = DirectCast(dr2.Item("filedata"),Byte())

        End While
        conn.Close()


    End Sub

End Class

DGVSV = DataGridView

所以我已经上传了几个文件到我的数据库中。现在我想将这些文件从数据库下载回我的本地电脑。如何做到这一点？

在数据库中，这些文件保存为长二进制数据类型。

我已经上传了我的整套代码。看看它。你可以看到我设置的扩展名是所有类型的文件。