高手给看是怎么产生的“读取列序号“0”的尝试无效。通过 CommandBehavior.SequentialAccess 只能读取“2”或更大的列序号"

[zhangwanglan]

我是把数据库里的图片全部导入到wode文件夹下，提示错误“读取列序号“0”的尝试无效。通过 CommandBehavior.SequentialAccess 只能读取“2”或更大的列序号”是怎么回事，高手帮忙看下

 Dim db As String = "Data Source=lenovo-pc;Initial Catalog=wode;User ID=sa;password=123456"
        Using con As New SqlConnection(db)

            Dim com As New SqlCommand
            com.CommandText = "select * from 图片"
            com.Connection = con
            Dim buffer As Integer = 10000
            Dim outbyte(buffer - 1) As Byte
            Dim retval As Long
            Dim startindex As Long = 0
            Dim id As String = ""
            con.Open()
            Using Myreader As SqlDataReader = com.ExecuteReader(CommandBehavior.SequentialAccess)
                Do While Myreader.Read()
                    Dim h As String = Myreader.GetString(1)
                    Using fa As New FileStream("E:\wode\" & h & ".jpg", FileMode.OpenOrCreate, FileAccess.Write)
                        Using bw As New BinaryWriter(fa)
                            startindex = 0
                            retval = Myreader.GetBytes(0, startindex, outbyte, 0, buffer)（读取列序号“0”的尝试无效。通过 CommandBehavior.SequentialAccess 只能读取“2”或更大的列序号）
                            Do While retval = buffer
                                bw.Write(outbyte)
                                bw.Flush()
                                startindex += buffer
                                retval = Myreader.GetBytes(0, startindex, outbyte, 0, buffer)
                            Loop
                            bw.Write(outbyte, 0, CType(retval - 1, Integer))
                            bw.Flush()
                        End Using
                    End Using
                Loop
                MsgBox("导入长弓")

            End Using
        End Using

数据库里的列表
数据库里有两列，一个图片在第一列，文件名在第二列