vb.net 存取数据库中的图片

以MS自带的数据库Northwnd为例,其中有个表是Categories,有四个四段,其中有一个是Image类型的Picture字段.我们首先添加一张bmp图片到最后一行的Picture中,然后在读出来显示到Image控件中.

添加一个SqlDataAdapter1,用向导设置联接数据库为Northwnd,SQL语句为SELECT [Category ID], [Category Name], Description, Picture FROM Categories.生成一个数据集为dataset1. 然后添加两个按钮分别表示写图片到数据库和读数据库,还有一个Image控件用于显示图片.

添加以下代码

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
SqlDataAdapter1.Fill(DataSet11)
End Sub

'从数据库读取图片暂时存储为monkey.bmp,然后加载到image控件里面.
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles LoadPicFromDb.Click
        Try
            Dim data As Byte() = DataSet11.Tables(0).Rows(7).Item(3)
            Dim myfilestream As New System.IO.FileStream(Application.StartupPath & "\monkey.bmp", IO.FileMode.Create)
            myfilestream.Write(data, 0, data.Length)
            myfilestream.Close()
            PictureBox1.Image = New Bitmap(Application.StartupPath & "\monkey.bmp")
        Catch
        End Try
    End Sub

    '把C:\6.bmp写入库中,你可以改为自己的图片.
    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles InsertPicToDb.Click
        Dim myfilestream As New System.IO.FileStream("c:\6.bmp", IO.FileMode.Open)
        Dim data() As Byte
        ReDim data(myfilestream.Length - 1)
        myfilestream.Read(data, 0, myfilestream.Length)
        myfilestream.Close()
        DataSet11.Tables(0).Rows(7).Item(3) = data
        SqlDataAdapter1.Update(DataSet11.GetChanges())
    End Sub

         以MS自带的数据库Northwnd为例,其中有个表是Categories,有四个四段,其中有一个是Image类型的Picture字段.我们首先添加一张bmp图片到最后一行的Picture中,然后在读出来显示到Image控件中.

添加以下代码

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
SqlDataAdapter1.Fill(DataSet11)
End Sub

可以不用存临时文件。
例子：
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim ss As New System.IO.MemoryStream

        Me.PictureBox1.Image.Save(ss, System.Drawing.Imaging.ImageFormat.Jpeg)
        Dim B(ss.Length) As Byte
        B = ss.GetBuffer
        Ds2.Tables(0).Rows(0)("Picture") = B
        SqlDataAdapter1.Update(Ds2)
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Dim B() As Byte = Ds2.Tables(0).Rows(0)("Picture")
        Dim S As New System.IO.MemoryStream(B)
        Me.PictureBox1.Image = System.Drawing.Image.FromStream(S)
    End Sub