Hi Lars OK, after much poking around the schema, I realize that I have misinterpreted something. You have to impose one of two constraints. Either: 1. A DataElement can only (must) be a member of one DataSet; or 2. A DataElement can only (must) have one PeriodType.
And also a DataValue already has a period associated, so there is no need to also associate the PeriodType explicitly - ie. my suggestion above is nonsense. If you could impose (1) it would be cleaner as this would implicitly enforce (2) but I can see it might be more disruptive to the existing corpus of data. Though I am still nagged by doubt that there seems to be some redundancy in your proposal and also that it will be hard to enforce constraints at the database level ie. you require a well behaved application. And in the end it is the datavalues which are to be aggregated, reported on etc. If we cannot impose (1), or we shouldn't or we don't want to, then is it instead possible to think of a "fully qualified" DataElement as DataSet::DataElement? Practically this means having DataSet, DataElement and Period association with the DataValue. The advantage would be that we still only need to associate the PeriodType with the DataSet. Of course this probably does not work if DataElements are meant to be aggregated across different DataSets as it assumes a DataElement in one DataSet is not the same apple or orange as the same DataElement in another DataSet. If this is the case, then I do agree, the only solution is to make the schema change you suggest. Regards Bob PS. I am still looking for sample datasets. I tried the link at http://208.76.222.114/confluence/display/DHIS2/Downloads but it is broken. Can anyone please point me to some. 2009/3/17 Lars Helge Øverland <[email protected]>: > >> >> >> If I read you correctly, you are effectively moving the association >> down from the dataset to the dataelement. > > Actually this implies keeping the DataSet-PeriodType association as you need > it to enforce that only DataElements with corresponding PeriodTypes are > members. > > Lars > > > _______________________________________________ Mailing list: https://launchpad.net/~dhis2-devs Post to : [email protected] Unsubscribe : https://launchpad.net/~dhis2-devs More help : https://help.launchpad.net/ListHelp
