sql - What are alternatives to update/delete records with a key that references multiple tables? -


i reading on threads in so, , found out example party table below incorrect because have foreign key referencing 2 tables cannot do. thought whole idea of foreign keys make sure if update or delete in 1 table, row references foreign key gets updated or deleted. doesn't whole idea of limiting foreign key reference single table kind of kill idea? way update/delete records among tables when delete key referenced in other tables?

in mobile app right now, if "party" deleted or renamed, write query check appropriate tables , delete table, condition wherever need to. "normal" way? thought on delete cascade or on update cascade trick, if it's single referenced table, might doing query on each appropriate table.

i guess question might be, if have foreign key in multiple tables, sign of bad design? foreign key in multiple tables supposed rare occurrence?

create table party (       partyname varchar(30) not null,       pcname    varchar(30) not null,       primary key (partyname, pcname),       foreign key (partyname, pcname) references pc_basic (partyname, pcname) on delete cascade,       foreign key (partyname, pcname) references pc_stats (partyname, pcname) on delete cascade       );      create table pc_basic (       partyname varchar(30) not null,       pcname    varchar(30) not null,       init      integer not null,       ac        integer not null       primary key (partyname, pcname)     );      create table pc_stats (       str integer not null,       dex integer not null,       partyname varchar(30) not null,       pcname varchar(30) not null,       primary key (partyname, pcname)       );

yes, in case indicates there problem relational schema design.

all 3 of tables use same primary key. expect 1 of tables "master" or important table whatever represented combination of (partyname, pcname). other 2 tables may contain supplemental, or perhaps optional information, related master table. if so, 2 supplemental tables each have single foreign key master table only.

if doesn't describe how data these tables related in business case, please provide more details. instance, if data 3 tables required in cases, option combine 3 single table.

it not always design issue have multiple foreign keys different tables, in cases foreign keys involve different set of columns.


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