Pinturikkio Pinturikkio - 2 months ago 24
Vb.net Question

VB.NET: Retrive an image (blob) from MySQL DB

I've a field called "Foto" in MySQL DB. This field is a blob. When I used SQL Server, the following code worked:

Dim conn As New MySqlConnection
conn.ConnectionString = ConnectionString
Dim cmd As New MySqlCommand
cmd.Connection = conn
conn.Open()
cmd.CommandText = "SELECT Foto FROM MyTable WHERE ID = '" & IDtxt.ToString & "'"
Dim reader As MySqlDataReader

reader = cmd.ExecuteReader
While reader.Read
If (IsDBNull(reader("Foto"))) Then
frmCartaIdentitaView.pctImage.Image = Nothing
Else
Dim byteImage() As Byte = reader("Foto")
Dim frmImageView stmFoto As New System.IO.MemoryStream(byteImage)
frmImageView.pctImage.Image = Image.FromStream(stmFoto)
frmImageView.pctImage.SizeMode = PictureBoxSizeMode.Zoom
frmImageView.Show()
End If
End While


But now that I'm using mysql, is produced the following error: invalid parameter.

Answer

If your ID field is an integer, see if this gets you past that error. Instead of this:

cmd.CommandText = "SELECT Foto FROM MyTable WHERE ID = '" & IDtxt.ToString & "'"

Try this:

cmd.CommandText = "SELECT Foto FROM MyTable WHERE ID = " & ctype(int32,IDtxt).ToString