Mega Code Archive

 

Categories / PostgreSQL / Constraints

 

Adding constraints (FOREIGN KEY) to a table

postgres=# postgres=# postgres=# -- Creating the books table postgres=# postgres=# CREATE TABLE books ( postgres(#               id integer UNIQUE, postgres(#               title text NOT NULL, postgres(#               author_id  integer, postgres(#               subject_id integer, postgres(#               CONSTRAINT books_id_pkey PRIMARY KEY (id)); ERROR:  relation "books" already exists postgres=# postgres=# create table editions ( postgres(#              edition_id integer, postgres(#              book_id    integer postgres(#              ); CREATE TABLE postgres=# postgres=# postgres=# -- Adding constraints to a table postgres=# postgres=# ALTER TABLE editions postgres-#                  ADD CONSTRAINT foreign_book postgres-#                  FOREIGN KEY (book_id) REFERENCES books (id); ALTER TABLE postgres=# postgres=# drop table books cascade; NOTICE:  drop cascades to constraint foreign_book on table editions DROP TABLE postgres=# postgres=# drop table editions cascade; DROP TABLE postgres=#