sql - How to use two columns in a foreign key constraint -

i have 2 tables:

1. article
2. subscription

in article table have 2 columns make primary key: id, sl. in subscription table have foreign key 'idsl`.

i use constraint :

constraint fk_idsl    foreign key (idsl) references css_subscriptiongroup(id, sl) 

but when run query, getting error:

number of referencing columns in foreign key differs number of referenced columns, table x

in article table have 2 fields primary key: id,sl. in subscription table have foreign key 'idsl`

this design broken - apparent composite primary key in article(id, sl) has been mangled single compound foreign key in table subscription. isn't idea.

instead, need change design of table subscription include separate columns both id , sl, of same type article table, , create composite foreign key consisting of both columns, referencing article in same order primary key, e.g:

create table article (     id int not null,     sl varchar(50) not null,     -- other columns      constraint pk_article primary key(id, sl) -- composite primary key );  create table subscription (     -- other columns     id int not null, -- same type article.id     sl varchar(50) not null, -- same type article.sl      constraint fk_subscription_article foreign key(id, sl)           references article(id, sl) -- same order article pk ); 

edit

one thing consider here convention column named table.id or table.tableid should unique, , primary key table. however, since table article requires additional column sl in primary key, implies id isn't unique.