"alex b." <mailinglists1@gmx.de> writes:
> > Column "mp3checksum" of table "tcontent" needs a UNIQUE
> > constraint--does it have one?
>
> no it doesn't - because it is possible that the same exact file might
> be existent on multiple CDs...
> and therefore "mp3checksum" cannot have a UNIQUE constraint.
> am I right?
Then "mp3checksum" can't be a foreign key--a foreign key must be
unique in its own table. If "tcontent" has a primary key, use that as
the foreign key in in the other table; if it doesn't, you might want
to create a SERIAL column to serve as the primary key.
-Doug