PostgreSQL/Postgre SQL/Type

Create data type

postgres=#
postgres=#
postgres=# CREATE TYPE sum_prod AS (sum int, product int);
CREATE TYPE
postgres=#
postgres=# CREATE FUNCTION sum_n_product (int, int) RETURNS sum_prod
postgres-# AS "SELECT $1 + $2, $1 * $2"
postgres-# LANGUAGE SQL;
CREATE FUNCTION
postgres=#
postgres=# select sum_n_product (2, 1);
     REATE
 sum_n_product
---------------
 (3,2)
(1 row)
postgres=#
postgres=# drop function sum_n_product (int, int) cascade;
DROP FUNCTION
postgres=# drop type sum_prod cascade;
DROP TYPE
postgres=#
postgres=#

Create data type and use it as a column data type

postgres=# CREATE TYPE inventory_item AS (
postgres(#    name            text,
postgres(#    supplier_id     integer,
postgres(#    price           numeric
postgres(# );
CREATE TYPE
postgres=#
postgres=# CREATE TABLE on_hand (
postgres(#    item      inventory_item,
postgres(#    count     integer
postgres(# );
CREATE TABLE
postgres=#
postgres=# INSERT INTO on_hand VALUES (ROW("fuzzy dice", 42, 1.99), 1000);
INSERT 0 1
postgres=#
postgres=# select * from on_hand;
          item          | count
------------------------+-------
 ("fuzzy dice",42,1.99) |  1000
(1 row)
postgres=#
postgres=# drop table on_hand;
DROP TABLE
postgres=# drop type inventory_item;
DROP TYPE
postgres=#
postgres=#

Declaration of Composite Types

postgres=#
postgres=# -- Declaration of Composite Types
postgres=#
postgres=# CREATE TYPE complex AS (
postgres(#    r       double precision,
postgres(#    i       double precision
postgres(# );
CREATE TYPE
postgres=#
postgres=#
postgres=# drop type complex;
DROP TYPE
postgres=#

Row function with defined data type

postgres=#
postgres=# CREATE TYPE inventory_item AS (
postgres(#    name            text,
postgres(#    supplier_id     integer,
postgres(#    price           numeric
postgres(# );
CREATE TYPE
postgres=#
postgres=# CREATE TABLE on_hand (
postgres(#    item      inventory_item,
postgres(#    count     integer
postgres(# );
CREATE TABLE
postgres=#
postgres=# INSERT INTO on_hand VALUES (ROW("fuzzy dice", 42, 1.99), 1000);
INSERT 0 1
postgres=#
postgres=# select * from on_hand;
          item          | count
------------------------+-------
 ("fuzzy dice",42,1.99) |  1000
(1 row)
postgres=#
postgres=# drop table on_hand;
DROP TABLE
postgres=# drop type inventory_item;
DROP TYPE
postgres=#

Using the %TYPE attribute

postgres=#
postgres=#
postgres=#
postgres=# CREATE TABLE "authors" (
postgres(#      "id" integer NOT NULL,
postgres(#      "last_name" text,
postgres(#      "first_name" text,
postgres(#      Constraint "authors_pkey" Primary Key ("id")
postgres(# );
NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index "authors_pkey" for table "authors"
CREATE TABLE
postgres=#
postgres=#
postgres=# insert into authors values (1111,  "Martin",       "Jason");
INSERT 0 1
postgres=# insert into authors values (1212,  "Worsley",      "Robert");
INSERT 0 1
postgres=# insert into authors values (15990, "Mathews",      "John");
INSERT 0 1
postgres=# insert into authors values (25041, "Smith",       "Williams");
INSERT 0 1
postgres=# insert into authors values (16,    "Alcott",       "May");
INSERT 0 1
postgres=# insert into authors values (4156,  "King",         "Stephen");
INSERT 0 1
postgres=# insert into authors values (1866,  "Herbert",      "Margaret");
INSERT 0 1
postgres=# insert into authors values (1644,  "Hogarth",      "Celia");
INSERT 0 1
postgres=# insert into authors values (2031,  "Brown",        "Wise");
INSERT 0 1
postgres=# insert into authors values (115,   "Poe",          "Allen");
INSERT 0 1
postgres=# insert into authors values (7805,  "Lutz",         "Mark");
INSERT 0 1
postgres=# insert into authors values (7806,  "Rice",         "Tom");
INSERT 0 1
postgres=# insert into authors values (1533,  "Black",        "Chris");
INSERT 0 1
postgres=# insert into authors values (1717,  "Brite",        "Linda");
INSERT 0 1
postgres=# insert into authors values (2112,  "Larry",        "Edward");
INSERT 0 1
postgres=# insert into authors values (2001,  "Clarke",       "Alison");
INSERT 0 1
postgres=# insert into authors values (1213,  "Green",        "Mary");
INSERT 0 1
postgres=#
postgres=# select * from authors;
  id   | last_name | first_name
-------+-----------+------------
  1111 | Martin    | Jason
  1212 | Worsley   | Robert
 15990 | Mathews   | John
 25041 | Smith     | Williams
    16 | Alcott    | May
  4156 | King      | Stephen
  1866 | Herbert   | Margaret
  1644 | Hogarth   | Celia
  2031 | Brown     | Wise
   115 | Poe       | Allen
  7805 | Lutz      | Mark
  7806 | Rice      | Tom
  1533 | Black     | Chris
  1717 | Brite     | Linda
  2112 | Larry     | Edward
  2001 | Clarke    | Alison
  1213 | Green     | Mary
(17 rows)
postgres=#
postgres=# drop function get_author(text);
DROP FUNCTION
postgres=#
postgres=# -- Using the %TYPE attribute
postgres=#
postgres=# CREATE FUNCTION get_author (text) RETURNS text AS "
postgres"#   DECLARE
postgres"#       -- Declare an alias for the function argument,
postgres"#       -- which should be the first name of an author.
postgres"#      f_name ALIAS FOR $1;
postgres"#      l_name authors.last_name%TYPE;
postgres"#   BEGIN
postgres"#      SELECT INTO l_name last_name FROM authors WHERE first_name = f_name;
postgres"#
postgres"#      return f_name || "" "" || l_name;
postgres"#
postgres"#   END;
postgres"# " LANGUAGE "plpgsql";
CREATE FUNCTION
postgres=#
postgres=# -- Results of the get_author(?) function
postgres=#
postgres=# SELECT get_author("Jason");
  get_author
--------------
 Jason Martin
(1 row)
postgres=#
postgres=# drop table authors;
DROP TABLE
postgres=#
postgres=#