有人检查我的代码插入图像到数据库中。我知道有一些错误,但无法弄清楚。当我运行代码时,它的工作,但当我点击完成按钮,它总是说NullReferenceException
这里是我有什么用longblob数据类型在mysql数据库中插入图像
Imports MySql.Data.MySqlClient
Imports System.IO
Public Class adminreg
Dim con As MySqlConnection
Dim cmd As MySqlCommand
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim reader As MySqlDataReader
Dim mstream As New System.IO.MemoryStream
PictureBox1.Image.Save(mstream, System.Drawing.Imaging.ImageFormat.Jpeg)
Dim arrImage() As Byte = mstream.GetBuffer()
mstream.Close()
con = New MySqlConnection
con.ConnectionString = "server=localhost;userid=root;password=1234;database=dat"
Try
con.Open()
Dim query As String
query = "insert into dat.login (idlogin,user,password,name,position,ownpic) values ('" & id.Text & "','" & usertxt.Text & "','" & passtxt.Text & "','" & nmetxt.Text & "','" & postxt.Text & "',@ownpic)"
cmd.Parameters.AddWithValue("@ownpic", arrImage)
cmd = New MySqlCommand(query, con)
reader = cmd.ExecuteReader
MessageBox.Show("Data Saved")
con.Close()
Catch ex As MySqlException
MessageBox.Show(ex.Message)
Finally
con.Dispose()
End Try
End Sub
Private Sub adminreg_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
End Sub
Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
OpenFileDialog1.Filter = "imahe lang (*.jpg, *.bmp, *.png) | *.jpg; *.bmp; *.png| all files (*.*) | *.*"
If OpenFileDialog1.ShowDialog <> Windows.Forms.DialogResult.Cancel Then
PictureBox1.Image = Image.FromFile(OpenFileDialog1.FileName)
End If
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
Login.Show()
Me.Hide()
End Sub
End Class
任何建议非常感谢,谢谢... ...只是一个初学者在VB.net
的NullReferenceException是未处理 –