如何使用vb.net和adodb连接在mysql数据库中插入图像 [英] how to insert image in mysql database using vb.net and adodb connection

问题描述

我想使用vb.net 2008中的adodb连接将图像插入到mysql数据库中.

I want to insert an image into a mysql database using the adodb connection in vb.net 2008.

我正在使用选择查询将数据插入数据库，这是我添加或保存数据的代码...

I am using a select query to insert data into database, here is my code for adding or saving data...

    rs.Open("select * from registration where Debt_ID = '" & txtDebt_ID.Text & "' ", cnn, ADODB.CursorTypeEnum.adOpenStatic, ADODB.LockTypeEnum.adLockPessimistic)
    If rs.RecordCount = 1 Then
        MsgBox("ID already exist!", MsgBoxStyle.Exclamation, vbOK)
        rs.Close()
        cnn.Close() 

        Exit Sub
    Else

        rs.AddNew()
        rs.Fields("Debt_ID").Value = txtDebt_ID.Text
        rs.Fields("LastName").Value = txt_Lastname.Text
        rs.Fields("firstName").Value = txt_Firstname.Text
        rs.Fields("MiddleName").Value = txt_Middlename.Text
        rs.Fields("age").Value = txt_Age.Text
        rs.Fields("birthdate").Value = txt_Birthdate.Text
        rs.Fields("civil_status").Value = txtCivil_status.Text
        rs.Fields("address").Value = txt_Address.Text
        rs.Fields("occupation").Value = txt_Address.Text
        rs.Fields("contact_no").Value = txt_Contact.Text
        'rs.Fields("picture").Value = PictureBox1.Image
        rs.Save()
        rs.Close()
    End If

我想将数据库中的图像添加到现场图片中，并且我将blob用作其数据类型，我也想从数据库中检索该图像并将其显示在图片框中...有人可以吗?帮助解决我的问题.

I wanted to add an image on the database into the field picture and I'm using blob as my datatype for it, I also want to retrieve the image from the database and display it in a picturebox... can someone please help regarding my problem.

预先感谢...

推荐答案

无论使用哪种数据访问技术或数据库，都需要先将am Image转换为Byte，然后再保存.检索时，将Byte数组转换回Image.

Regardless of what data access technology or database you use, you need to convert am Image to a Byte first and then save that. On retrieval, you convert the Byte array back to an Image.

要保存:

Dim connection As New SqlConnection("connection string here")
Dim command As New SqlCommand("UPDATE MyTable SET Picture = @Picture WHERE ID = 1", connection)

'Create an Image object.'
Using picture As Image = Image.FromFile("file path here")
    'Create an empty stream in memory.'
    Using stream As New IO.MemoryStream
        'Fill the stream with the binary data from the Image.'
        picture.Save(stream, Imaging.ImageFormat.Jpeg)

        'Get an array of Bytes from the stream and assign to the parameter.'
        command.Parameters.Add("@Picture", SqlDbType.VarBinary).Value = stream.GetBuffer()
    End Using
End Using

connection.Open()
command.ExecuteNonQuery()
connection.Close()

要检索:

Dim connection As New SqlConnection("connection string here")
Dim command As New SqlCommand("SELECT Picture FROM MyTable WHERE ID = 1", connection)

connection.Open()

Dim pictureData As Byte() = DirectCast(command.ExecuteScalar(), Byte())

connection.Close()

Dim picture As Image = Nothing

'Create a stream in memory containing the bytes that comprise the image.'
Using stream As New IO.MemoryStream(pictureData)
    'Read the stream and create an Image object from the data.'
    picture = Image.FromStream(stream)
End Using

该示例适用于ADO.NET和SQL Server，但是无论如何，使用MemoryStream进行转换的原理都是相同的.

That example is for ADO.NET and SQL Server but the principle of using a MemoryStream for the conversion is the same regardless.

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