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