composite primary key

The so-called composite primary key means that the primary key of your table contains more than one field,
such as the name and id fields above
create table test
(
name varchar(19),
id number,
value varchar(10),
primary  key  (name,id)
)

The combination is the composite primary key of your test table.
It appears because your name field may have the same name, so add the ID field to ensure the uniqueness of your records. In
general, the field length and number of fields of the primary key the less the better