VB.NET 操作 ACCESS OLE 字段内容

数据库结构:
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test.mdb [放在BIN目录下]
表 test(id 自动编号, img OLE)
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代码:
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使用 一个 openfiledialog ,两个 picturebox

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Imports System.IO
Public Class Form1
    Inherits System.Windows.Forms.Form

    Dim cnn As Data.OleDb.OleDbConnection

    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        Me.Dispose(True)
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        If OpenFileDialog1.ShowDialog = DialogResult.OK Then
            PictureBox1.Image = Image.FromFile(OpenFileDialog1.FileName)
        End If
    End Sub

    Private Sub DBInit()
        Try
            cnn = New Data.OleDb.OleDbConnection("Provider=Microsoft.JET.OLEDB.4.0;Data Source=" & Application.StartupPath & "\test.mdb")
            cnn.Open()
        Catch exp As OleDb.OleDbException
            MsgBox(exp.Message)
            End
        End Try
    End Sub

    Private Sub DBRelease()
        cnn.Close()
        cnn = Nothing
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        If PictureBox1.Image Is Nothing Then
            MsgBox("请先选择图片", MsgBoxStyle.Exclamation)
            Exit Sub
        End If
        Dim fs As FileStream = New FileStream(OpenFileDialog1.FileName, FileMode.Open, FileAccess.Read)
        Dim bt(fs.Length) As Byte
        fs.Read(bt, 0, fs.Length)
        fs.Close()
        fs = Nothing
        Dim oleCmd As OleDb.OleDbCommand = New OleDb.OleDbCommand
        DBInit()
        oleCmd.Connection = cnn
        oleCmd.CommandType = CommandType.Text
        oleCmd.CommandText = "INSERT INTO test (img) VALUES (@img)"
        oleCmd.Parameters.Add("@img", OleDb.OleDbType.Binary).Value = bt
        oleCmd.ExecuteNonQuery()
        oleCmd = Nothing
        DBRelease()
        MsgBox("图片插入成功")
    End Sub

    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        Dim oleCmd As OleDb.OleDbCommand = New OleDb.OleDbCommand("SELECT img FROM test WHERE id=1")
        oleCmd.CommandType = CommandType.Text
        DBInit()
        oleCmd.Connection = cnn
        Dim dr As OleDb.OleDbDataReader = oleCmd.ExecuteReader(CommandBehavior.SingleRow)
        If dr.Read Then
            If Not IsDBNull(dr.Item(0)) Then
                Dim bt() As Byte = dr.Item(0)
                Dim ms As MemoryStream = New MemoryStream(bt)
                PictureBox2.Image = Image.FromStream(ms)
            Else
                MsgBox("无图片")
            End If
        Else
            MsgBox("无数据")
        End If
        dr.Close()
        dr = Nothing
        oleCmd = Nothing
        DBRelease()
    End Sub
End Class

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