Is there any way to retrieve the attachment file from SQL database and put it back to an attachment clip control?
When using attachments in their default configuration, attachements can been added to folders either from a client machine (via a client app) or from a location accessable to the engine server (and the service account the engine is running as).
Custom code would be need to extract the file from the SQL Server to a location accessable by the engine. Then you could use the "Get Attachment" activity to add it to a folder...