如题!!!!请高手详细点解答!!最好有实例子!!

[此贴子已经被作者于2006-12-28 10:34:48编辑过]

将图片文件..读到一个二进制数组中..然后..插入到数据库..就行了.

<注意在看的时候,也没有必要全部看,首先看骨架,然后在看图片怎么保存到数据库中的就行了,另外,这里涉及到了fileSream流,主要是用来读取数据,与此相关的还有网络方面的NetworkStream,呵呵,还有很多)
微软的SQL SERVER数据库的Image、text等字段都属于二进制的大对象。这些对象的存取和其他轻型对象略有不同。比如，我们打开一个数据表的时候，普通类型的字段都可以看见，而Image类型的字段却不行，只能通过编程的方法来读取。这篇资料就是介绍怎样用vb.NET来向sql server数据库中存放图片，怎样从数据库中取出图片浏览
这个例程用到了 sql server自带的northwind数据库，其中employees（职员）数据表有一个字段“photo”，是用来存放照片的，里面有9条记录，我费了半天力气，想去看看那9个人图片，就是看不见。现在猜测，这些人的photo根本就是空的。所以，我决定添加一些新的记录。
在这个例程里，我实现了一个简单的WinForm程序，这个程序通过点击“Open”按钮选择一个图片文件（bmp或jpg），并显示在图形控件PictureBox中。通过“Save”按钮存入数据库。点击“View”CheckBox可以切换到浏览状态，观看存入数据库的图片。
微软.NET Framework的System.IO命名空间下给我们提供了一个FileStream文件流类。我们可以使用这个文件流对二进制大对象轻松进行读写。由于对二进制大对象使用的流操作，所以对于任何文件都具有通用性。读写文本文件也可以这么做。
步骤：

1、 先来看一下northwind数据库中employees表结构

2、 知道.net连接sql server的方法嘛，不知道的话，看看我写的“ado.net中的connection对象”吧。读懂下面这几句没问题吧：

Dim conn as new sqlconnection(“server=localhost;database=northwind;Integrated Security=true;”

Dim sqlcomm As New SqlCommand

sqlcomm.Connection = conn

sqlcomm.CommandText = "INSERT INTO employees (lastname,firstname,photo) VALUES (@lastname,@firstname,@photo)"

Dim prm1 As New SqlParameter("@lastname", txtLN.Text)

Dim prm2 As New SqlParameter("@firstname", txtFN.Text)

Dim prm3 As New SqlParameter("@photo", SqlDbType.VarBinary, Int(fs.Length), _ ParameterDirection.Input, False, 0, 0, "", DataRowVersion.Current, Data)

sqlcomm.Parameters.Add(prm1)

sqlcomm.Parameters.Add(prm2)

sqlcomm.Parameters.Add(prm3)
3、新建一个windows应用程序窗体
4、 声明类级的变量。找到设计期产生的代码部分，把下面的语句加到变量声明后面。什么？不知道变量声明在哪儿?不会吧！

Private fs As FileStream

Private ds As DataSet

Private conn As New SqlConnection("server=localhost;database=northwind;integrated security=true;")

Private currentpos As Integer = 9

5、 开始写代码了。首先是form_load

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

btnOpen.Enabled = True

btnSave.Enabled = True

btnBack.Enabled = False

btnForward.Enabled = False

End Sub

6、 open按钮的点击事件代码：

Private Sub openbtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnOpen.Click

Dim Opendlg As New OpenFileDialog

Opendlg.Title = "Select a picture file"

Opendlg.Filter = "(*.bmp)|*bmp|(*.jpg)|*.jpg"

Opendlg.ShowDialog()

lblPath.Text = Opendlg.FileName.ToString()

fs = New FileStream(Opendlg.FileName.ToString(), FileMode.Open, FileAccess.Read)

PictureBox1.Image = Image.FromFile(Opendlg.FileName.ToString())

End Sub

7、 save按钮的点击事件代码

Private Sub savebtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click

Dim sqlcomm As New SqlCommand

sqlcomm.CommandText = "INSERT INTO employees (lastname,firstname,photo) VALUES (@lastname,@firstname,@photo)"

sqlcomm.Connection = conn

Dim Data(fs.Length) As Byte

fs.Read(Data, 0, Int(fs.Length))

Dim prm1 As New SqlParameter("@lastname", txtLN.Text)

Dim prm2 As New SqlParameter("@firstname", txtFN.Text)

Dim prm3 As New SqlParameter("@photo", SqlDbType.VarBinary, Int(fs.Length), ParameterDirection.Input, False, 0, 0, "", DataRowVersion.Current, Data)

sqlcomm.Parameters.Add(prm1)

sqlcomm.Parameters.Add(prm2)

sqlcomm.Parameters.Add(prm3)

Try

conn.Open()

sqlcomm.ExecuteNonQuery() '执行插入语句

conn.Close()

fs.Close()

Catch ex As Exception

MsgBox(ex.Message)

End Try

End Sub

8、 选择view状态的事件代码

Private Sub CheckBox1_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CheckBox1.CheckedChanged

If CheckBox1.Checked = True Then

btnOpen.Enabled = False

btnSave.Enabled = False

btnBack.Enabled = True

btnForward.Enabled = True

currentpos = 9

Dim sqlcomm As New SqlCommand

sqlcomm.CommandText = "SELECT employeeId, photo FROM employees ORDER BY employeeId"

sqlcomm.Connection = conn

Dim da As New SqlDataAdapter(sqlcomm)

Try

conn.Open()

ds = New DataSet

da.Fill(ds, "employees")

conn.Close()

Catch sqlEx As SqlException

MsgBox(sqlEx.Message)

End Try

Dim data() As Byte = ds.Tables("employees").Rows(9)("photo")

Dim stmphoto As New MemoryStream(data)

PictureBox1.Image = Image.FromStream(stmphoto)

Else

btnOpen.Enabled = True

btnSave.Enabled = True

btnBack.Enabled = False

btnForward.Enabled = False

End If

End Sub

9、 “>>”按钮点击事件代码

Private Sub forward_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnForward.Click

If currentpos = ds.Tables("employees").Rows.Count - 1 Then

Return

Else

currentpos += 1

Dim data() As Byte

data = ds.Tables("employees").Rows(currentpos)("photo")

Dim stmphoto As New MemoryStream(data)

PictureBox1.Image = Image.FromStream(stmphoto)

End If

End Sub

10、 “<<”按钮点击事件代码

Private Sub back_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnBack.Click

If currentpos = 9 Then

Return

Else

currentpos -= 1

End If

Dim Data() As Byte

Data = ds.Tables("employees").Rows(currentpos)("photo")

Dim stmPhoto As New MemoryStream(Data)

PictureBox1.Image = Image.FromStream(stmPhoto)

End Sub

11、 好了，可以运行看看了。

LOOKING...............

[此贴子已经被作者于2007-1-6 17:12:43编辑过]