Retrieving images from the database & displaying

[mike55]

Hi,

 

I am storing images in my database, where I am using 3 columns for each image, 1. imageName as an nvarchar(50), 2. imageData as an image, and 3. imageType as an nvarchar(100).

 

I have successfully inserted the images into the database, only problem that I am having is that I am unable to do any sort of compression on the images, but that's a different problem. The issue that I am having is that if I try and retrieve two images from the database and display them at the same time, in some cases only 1 image is displayed while in other cases no image is displayed.

 

To display the images, I have created a web control with two html image controls with runat="server", both these controls have the image url set to a different .aspx page which use the following code to retrieve the image from the database and display it:

Private Sub LoadImage()
       Dim myReader As Byte()
       Dim content As String = String.Empty

       myReader = dbConnection.RetrievePhoto(Request.QueryString("pid").ToString, 0, content)

       Try
           Response.ContentType = content
           If Not myReader Is Nothing Then
               Response.BinaryWrite(myReader)
           Else
               Response.WriteFile("images/Notfound.jpg")
           End If
       Catch ex As Exception

       End Try
   End Sub

 

In the event that the images don't display, I have manually gone to the pages which runs the above code, and I have confirmed that the code is running correctly and displaying the images.

 

Any suggestions on how to correct this problem? I think that it may be down to the size of the images, so they are causing some sort of timeout during execution of my code, but I cannot be positive.

 

Mike55.

[PlausiblyDamp]

Could you post the code to the dbConnection.RetrievePhoto method - if anything that is likely to be where the problem lies.

[mike55]

Here it is:

Public Shared Function RetrievePhoto(ByVal id As String, ByVal photo As Int16, ByRef content As String) As Byte()
       Dim sqlCmd As SqlCommand
       connection = New SqlConnection(consql)

       Try
           'Open the database connection.
           If connection.State = ConnectionState.Closed Then
               connection.Open()
           End If
       Catch ex As Exception
           GoTo end1
       End Try

       Try
           myDsDataset = New DataSet
           myAdapter = New SqlDataAdapter
           Dim myDataReader As SqlDataReader = Nothing
           'Retrieve the data.
           Select Case photo
               Case 0
                   sqlCmd = New SqlCommand("SELECT (Pict1) as Pict, (Content1) as Content FROM Lands where ref = " & id & "", connection)
                   myDataReader = sqlCmd.ExecuteReader
               Case 1
                   sqlCmd = New SqlCommand("SELECT (Pict2) as Pict, (Content2) as Content FROM Lands where ref = " & id & "", connection)
                   myDataReader = sqlCmd.ExecuteReader
           End Select

           Dim myArray As Byte() = Nothing

           Do While myDataReader.Read
               If myDataReader("Pict") Is System.DBNull.Value Then
                   myArray = Nothing
                   GoTo xyz
               End If
               myArray = myDataReader.Item("Pict")
               content = myDataReader.Item("Content")
           Loop
xyz:
           'Return the data back to the user.
           Return myArray

       Catch ex As Exception
       Finally
           'Close the database connection.
           If connection.State = ConnectionState.Open Then
               connection.Close()
           End If
       End Try
end1:
   End Function

 

Mike55.

[PlausiblyDamp]

Nothing obvious jumps out as being a potential cause of the problem....

 

How large are the images roughly and if they are large what format are they being stored in (jpeg, png etc.) as time-outs are probably the main culprit here.