On Wed, Jun 27, 2007 at 02:12:03PM +0200, Karsten Hilbert wrote: > Subject: Re: [Gnumed-devel] forms handling / NetEpi > User-Agent: Mutt/1.5.13 (2006-08-11) > > On Wed, Jun 27, 2007 at 07:02:27AM +1000, Tim Churches wrote: > > > >> Easier extensibility of the form definitions/metadata, > > > I can see that. Put IOW: it seems safer to update data in > > > deployed databases rather than requiring the databases > > > themselves to be modified, eg. when one needs a new "field" > > > in the form metadata definition. > > > > > > It *can* be done via ALTER TABLE but I agree it sounds safer > > > to rather do UPDATE ... WHERE ... ; > > > > What if the update to a form which has already been used to collect data > > involves the removal of a column? If you use ALTER TABLE, all the data > > collected in that form field/column is now gone... where's the undo button? Oh, I just noticed a misconception here:
An ALTER TABLE on the form definition table wouldn't even affect any data column in any way. It would affect *attributes* on a field definition to exist/not exist. The actual field defs themselves would be rows in that table. Actual *data* for said fields would be foreign keyed to the field def so as long as there's corresponding data deletion of a field def could be "guarantueed" to not occur. Karsten -- GPG key ID E4071346 @ wwwkeys.pgp.net E167 67FD A291 2BEA 73BD 4537 78B9 A9F9 E407 1346 _______________________________________________ Gnumed-devel mailing list [email protected] http://lists.gnu.org/mailman/listinfo/gnumed-devel
