Il 20/12/2013 16:32, Mark Rotteveel ha scritto: > On Fri, 20 Dec 2013 14:15:38 +0100, Fulvio Senore <[email protected]> > wrote: >> I have two tables, for example TableA and TableB. >> >> Each row of TableA contains a foreign key to a row of TableB. >> This a 1 to 1 relation, so each row of TableA is linked to one different > >> row of TableB. >> The foreign key field can also be NULL, in this case the TableA row is >> not connected to a TableB row. >> >> All TableB rows depend logically on TableA rows, so all TableB rows >> should be linked by a TableA row. >> >> I would like to check for program errors during development, so I would >> like to know if there are "orphans" TableB rows. >> >> May somebody suggest me a good way to find the rows in TableB that are >> not connected from any row in TableA? > > To me it sounds like you have the dependencies reversed: TableB should > have a foreign key to TableA, and not the other way around. >
Many thanks to everybody who helped with my question. I was also wondering if I can find a better design, but it's good to know how to solve my problem. Fulvio Senore
