大家帮帮忙啊，从数据库中读取图片的问题！

[tjuzhoukang]

Imports System.Data.SqlClient
Imports System
Imports System.IO
Imports System.Text

Public Class Form1
Dim mystr As String = "data source=WWW-7EDE22A8BFA;initial catalog=school;persist security info=true;user id=sa;password=11"
Dim myconn As New SqlConnection(mystr)
Dim i As Integer


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

End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
myconn.Open()
Dim mysql As String = "select * from picture where 编号='1'"
Dim myda As SqlDataAdapter = New SqlDataAdapter
Dim mycmd As SqlCommand = New SqlCommand(mysql, myconn)
myda.SelectCommand = mycmd

Dim myds As New DataSet

myda.Fill(myds, "picture")
myconn.Close()

Dim data() As Byte = myds.Tables("picture").Rows(0).Item(1)
Dim stmphoto As New MemoryStream(data)

PictureBox1.Image = Image.FromStream(stmphoto)

End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
i = 1
myconn.Open()
Dim mysql As String = "select * from picture where 编号='1'"
Dim myda As SqlDataAdapter = New SqlDataAdapter
Dim mycmd As SqlCommand = New SqlCommand(mysql, myconn)
myda.SelectCommand = mycmd

Dim myds As New DataSet


myda.Fill(myds, "picture")
myconn.Close()




Dim data() As Byte = myds.Tables("picture").Rows(0).Item(1)
Dim stmphoto As New MemoryStream(data)

PictureBox1.Image = Image.FromStream(stmphoto)


End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
i += 1
myconn.Open()
Dim mysql As String = "select * from picture where 编号='1'"
Dim myda As SqlDataAdapter = New SqlDataAdapter
Dim mycmd As SqlCommand = New SqlCommand(mysql, myconn)
myda.SelectCommand = mycmd
Dim myds As New DataSet
myda.Fill(myds, "picture")
myconn.Close()

Try

Dim data() As Byte = myds.Tables("picture").Rows(0).Item(i)



Dim stmphoto As New MemoryStream(data)

PictureBox1.Image = Image.FromStream(stmphoto)

Catch ex As Exception
MsgBox("最后一张", MsgBoxStyle.OkOnly, "信息提示")

i -= 1
End Try


End Sub

Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
i -= 1
myconn.Open()
Dim mysql As String = "select * from picture where 编号='1'"
Dim myda As SqlDataAdapter = New SqlDataAdapter
Dim mycmd As SqlCommand = New SqlCommand(mysql, myconn)
myda.SelectCommand = mycmd
Dim myds As New DataSet
myda.Fill(myds, "picture")
myconn.Close()

Try

Dim data() As Byte = myds.Tables("picture").Rows(0).Item(i)



Dim stmphoto As New MemoryStream(data)

PictureBox1.Image = Image.FromStream(stmphoto)

Catch ex As Exception
MsgBox("最前一张", MsgBoxStyle.OkOnly, "信息提示")
i += 1


End Try
End Sub
End Class


这是我编写的一段从数据库往VB界面读取图片的程序，但是有个问题！

我的SQL Server数据库里面建了一个表picture，表里存的是二进制数据图片，picture表有N行，每一行有10列，就是每一行最多存10张图片。

但是往picture表里存图片的时候，我可能只存5张、6张或7张，但是还必须保证有10列，要保证表的容量。

这样当我执行程序时，如果读到某一行某一列的内容为NULL时，就会报错！

我就想知道，要如何在VB.NET程序里面判断数据表picture中某一行某一列的内容为空啊！找了好长时间，也没有解决的办法。

帮小弟出点注意吧，要怎么才能解决关于数据表中内容为空的问题啊！

[机器人]

Convert.IsDBNull 判断DB的空数据。