how to save a byte() to my SQLDatabase using VB.net - mysql

Question

I know that there are already a couple of questions which seems like my problem but I tried to copy a lot of it and tried but can’t get the resold I want.
Actually is my target to save an image from a Picture Box as Byte() into mySQL Database.
At first I tried the simple way like
Dim acCust As Image = pgbox.image
Dim picBytes() As Byte
Using ms As New MemoryStream
cust.Save(ms, cust.RawFormat)
picBytes = ms.ToArray()
End Using
but with this I run into a general GUI error so I copied the Picture at first like this
Dim rec As New Rectangle(0, 0, acCust.Width, acCust.Height)
Dim mus As New ImageFormatConverter
Dim muster As New Bitmap(rec.Width, rec.Height)
Dim cust As Image
Using grp = Graphics.FromImage(muster)
grp.DrawImage(acCust, New Rectangle(0, 0, rec.Width, rec.Height), rec, GraphicsUnit.Pixel)
cust = muster
End Using
If I use after that again the code
Dim picBytes() As Byte
Using ms As New MemoryStream
cust.Save(ms, cust.RawFormat)
picBytes = ms.ToArray()
End Using
sqlconection.Open()
Dim query As String = "INSERT INTO tblimg(img) VALUES ('#image');"
Dim com As New MySqlCommand(query, sqlconection)
com.Parameters.AddWithValue("image", picBytes)
com.ExecuteNonQuery()
sqlconection.Close()
everything looks sofa ok but if I read it like this
Dim imgData As Byte()
Dim sql As String = "SELECT img FROM tblimg"
sqlconection.Open()
Dim cmd As New MySqlCommand(sql, sqlconection)
Using rdr As MySqlDataReader = cmd.ExecuteReader
If rdr.HasRows Then
rdr.Read()
imgData = TryCast(rdr.Item("img"), Byte())
' in case this record has no image
If imgData IsNot Nothing Then
' ToDo: dispose of any previous Image
' create memstream from bytes
Using ms As New MemoryStream(imgData)
' create image from stream, assign to PicBox
pbbox.Image = CType(Image.FromStream(ms), Image)
End Using
End If
End If
End Using
I got an alarm message
Eine nicht behandelte Ausnahme des Typs "System.ArgumentException" ist in System.Drawing.dll aufgetreten.
Zusätzliche Informationen: Ungültiger Parameter.
(Sorry it's in German)
Has anybody an idea what and were it’s going wrong?
If I use the the picByts () in a new memory stream and convert it back to an image then I got the correct result. It seems like there is a problem with the up or download query
in my Server I use the variable type LongBlob

Answer 1

You save a Byte array to a database in exactly the same way as you save any other data. You write your SQL, you add a parameter to a command and you set its value. This:
Dim query As String = "INSERT INTO tblimg(img) VALUES ('#image');"
Dim com As New MySqlCommand(query, sqlconection)
com.Parameters.AddWithValue("image", picBytes)
is wrong. You only wrap literal strings in single quotes in SQL code. That should be like this:
Dim query As String = "INSERT INTO tblimg(img) VALUES (#image);"
Dim com As New MySqlCommand(query, sqlconection)
com.Parameters.AddWithValue("#image", picBytes)
No single quotes around the parameter in the SQL and use the actual parameter name when adding it to the command. I'd also recommend using Add rather than AddWithValue but that's a discussion for another time.