On Wed, Nov 19, 2003 at 01:36:17PM -0600, Antonio Gallardo wrote: > >> > - sometimes the db schema makes it impossible to use O/R tools > > Show me one. This also denote SQL can be abused. Just for the records, we > are currently building an accounting system and O/R works fine there. This > is the example you said: a 150+ tables. see http://marc.theaimsgroup.com/?l=xml-cocoon-dev&m=105957045726408&w=2
The second case is : Imagine you have table that describes building (Building) and then you have a table that describes the flat (Flat). Now you want to assign tasks: - visit the flat and do something - visit the whole building (each flat in the building) so you add some more tables: Task TaskBuilding TaskFlat You also have to add a TaskBuildingFlatVisited table to be able to report which flats have already been visited if a task was for the whole building. Now the problem: you cannot generate a report simply if you do just inserts into the TaskBuildingFlatVisited table, just because you know which flats HAVE been visited and it is very hard to query the database for a negated set (the flats that have not been visited have no corresponding records in the database). So the solution is simple: You extend TaskBuildingFlatVisited table with a visited_status column. Now you create a trigger on TaskBuilding table that for each building task insert you insert all corresponding flat references to TaskBuildingFlatVisited. Now if a user visits a flat you do not insert a record - you UPDATE an appropriate one. So now if you want to query for flats that have not been visited it is really simple. But now the database adds/deletes rows from database behind your back. AFAIU this messes up OJB tool completely. Or am I wrong maybe? > > Who said O/R mapping need to be wroten by hand? This is not a MUST > anymore. This is mainly why I go to Druid. Did you know Druid? If not here > is the link: http://druid.apache.org/ :-D This link does not work :) I've been looking at druid but there is one problem: Druid uses some weird technique to detect a JDBC driver in provided jar file. The problem is that Microsoft SQL Server JDBC driver consists of 3 jar files and even if you edit the druid configuration by hand it does not detect the driver class. > > Using Druid making an O/R mapping is a matter fo secs! Is this a problem? > Also + your Beans ready to be used. Well the Beans for JDO are a little > bit slower. But I am sure you will have in less than 2 mins you > database.jar ready to use. So where is the problem? :-DD If you advertise it so strongly I think I will have to try it but first I have to resolve a problem with the M$ JDBC driver. ouzo -- __ | / \ | Leszek Gawron // \\ \_\\ //_/ [EMAIL PROTECTED] _\\()//_ .'/()\'. Phone: +48(501)720812 / // \\ \ \\ // recursive: adj; see recursive | \__/ |
