Using foreign keys : FOREIGN KEY « Constraints « PostgreSQL

1. PostgreSQL
2. Constraints
3. FOREIGN KEY

Using foreign keys

postgres=#
postgres=# -- Foreign Keys
postgres=#
postgres=# CREATE TABLE cities (
postgres(#        city     varchar(80) primary key,
postgres(#        id       int
postgres(# );
NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index "cities_pkey" for table "cities"
CREATE TABLE
postgres=#
postgres=# CREATE TABLE weather (
postgres(#        city      varchar(80) references cities(city),
postgres(#        temp_lo   int,
postgres(#        temp_hi   int,
postgres(#        prcp      real,
postgres(#        date      date
postgres(# );
CREATE TABLE
postgres=#
postgres=# insert into cities values ('Berkeley', 0);
INSERT 0 1
postgres=#
postgres=# INSERT INTO weather VALUES ('Berkeley', 45, 53, 0.0, '1994-11-28');
INSERT 0 1
postgres=#
postgres=# drop table weather;
DROP TABLE
postgres=# drop table cities;
DROP TABLE
postgres=#
postgres=#
           
       

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