On Wed, 31 Aug 2011 16:20:24 +0200, Fulvio Senore <mail...@fsoft.it> wrote: > I didn't know anything about the N+1 query trap, but Google was my friend. > Yes, that is my problem, but I don't know how to find a better solution. > > My program shows 3 user selectable views. For each view a tree control > at the left shows a structure of "folders" and "subfolders" where images
> are organized. > > When I open a catalog I load the first 2 levels of items in the tree > controls, so that users can see all the first level items and they can > see if an item has sub-items so it can be expanded. > Further items loading in the tree controls happens when the user expands > an existing item. > > Of course if the user has a lot of items in the tree controls this leads > to an explosion of queries. This has never been a problem before, but I > realize that a better solution would be welcome. > > At the moment I enumerate all the first level items with a query, then I > execute a query for each item to find its sub-items. > Items are stored in a single table, with a parent-child relationship > created using a FATHER_ID field. > I probably need a better solution, but probably this question would be > better suited for the Firebird Support list. Not 100% sure, but it sounds like a recursive Common Table Expression might be your friend here. See for example http://mycodingexperience.blogspot.com/2011/04/common-table-expression-cte-and-tree.html (in Firebird you will need to use WITH RECURSIVE for this) Mark ------------------------------------------------------------------------------ Special Offer -- Download ArcSight Logger for FREE! Finally, a world-class log management solution at an even better price-free! And you'll get a free "Love Thy Logs" t-shirt when you download Logger. Secure your free ArcSight Logger TODAY! http://p.sf.net/sfu/arcsisghtdev2dev Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
