In message <b4gccq+41hn@...>, duilio_fos <irel_llc@...>
writes

>Lucas,
>
>>What you want to do can perfectly be done with foreign keys
>
>mmm...
>
>>you add a STAR table above your SYSTEM table, like:
>
>could you please expand on this ?
>
>I am afraid I didn't understand.
>
>We start with this database:
>
>create table Stars (
>Star_ID integer not null,
>System_ID integer,
>primary key (Star_ID)
>)
>
>create table Systems (
>System_ID integer not null,
>Planet_ID integer not null,
>primary key (System_ID,Planet_ID)
>)
>
>Are you suggesting to insert a 3th table btw Stars and Systems ?
>
>Please write the code of the new database.
>
>Thank you
>
>Duilio

create table Stars (
Star_ID integer not null,
primary key (Star_ID)
)

create table Planets (
Planet_ID integer not null,
Star_ID integer not null,
primary key (Planet_ID)
)

and presumably Star_Name, Star_Type
Planet_Name, Planet_Type...

I changed your primary key, because I don't like ID's to have any
meaning other than as an ID.

Now you link your tables via the Star_ID field - each planet must be
"connected to" a star.


--
Pete Clark

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