PostgreSQL/Store Procedure Function/Create Function

Add three parameters together in a function

postgres=#
postgres=# CREATE FUNCTION add_three_values(v1 anyelement, v2 anyelement, v3 anyelement)
postgres-# RETURNS anyelement AS $$
postgres$# DECLARE
postgres$#    result ALIAS FOR $0;
postgres$# BEGIN
postgres$#    result := v1 + v2 + v3;
postgres$#    RETURN result;
postgres$# END;
postgres$# $$ LANGUAGE plpgsql;
CREATE FUNCTION
postgres=#
postgres=# select add_three_values(1,2,3);
      REATE
 add_three_values
------------------
                6
(1 row)
postgres=#
postgres=# drop function add_three_values(v1 anyelement, v2 anyelement, v3 anyelement);
DROP FUNCTION
postgres=#
postgres=#

Case insensitive

postgres=#
postgres=# CREATE FUNCTION "first" () RETURNS integer AS "
postgres"#        DecLarE
postgres"#         oNe IntEgER := 1;
postgres"#        bEGiN
postgres"#         ReTUrn oNE;
postgres"#        eNd;
postgres"# " LANGUAGE "plpgsql";
CREATE FUNCTION
postgres=#
postgres=# select first();
 first
-------
     1
(1 row)
postgres=#

Create a simeple function

postgres=#
postgres=# CREATE TABLE employee (
postgres(#     ID         int,
postgres(#     name       varchar(10),
postgres(#     salary     real,
postgres(#     start_date date,
postgres(#     city       varchar(10),
postgres(#     region     char(1)
postgres(# );
CREATE TABLE
postgres=#
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (1,  "Jason", 40420,  "02/01/94", "New York", "W");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (2,  "Robert",14420,  "01/02/95", "Vancouver","N");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (3,  "Celia", 24020,  "12/03/96", "Toronto",  "W");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (4,  "Linda", 40620,  "11/04/97", "New York", "N");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (5,  "David", 80026,  "10/05/98", "Vancouver","W");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (6,  "James", 70060,  "09/06/99", "Toronto",  "N");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (7,  "Alison",90620,  "08/07/00", "New York", "W");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (8,  "Chris", 26020,  "07/08/01", "Vancouver","N");
INSERT 0 1
postgres=# insert into employee (ID, name,    salary, start_date, city,       region)
postgres-#               values (9,  "Mary",  60020,  "06/09/02", "Toronto",  "W");
INSERT 0 1
postgres=#
postgres=# select * from employee;
 id |  name  | salary | start_date |   city    | region
----+--------+--------+------------+-----------+--------
  1 | Jason  |  40420 | 1994-02-01 | New York  | W
  2 | Robert |  14420 | 1995-01-02 | Vancouver | N
  3 | Celia  |  24020 | 1996-12-03 | Toronto   | W
  4 | Linda  |  40620 | 1997-11-04 | New York  | N
  5 | David  |  80026 | 1998-10-05 | Vancouver | W
  6 | James  |  70060 | 1999-09-06 | Toronto   | N
  7 | Alison |  90620 | 2000-08-07 | New York  | W
  8 | Chris  |  26020 | 2001-07-08 | Vancouver | N
  9 | Mary   |  60020 | 2002-06-09 | Toronto   | W
(9 rows)
postgres=#
postgres=#
postgres=#
postgres=# CREATE FUNCTION "title" (integer)
postgres-# RETURNS text AS
postgres-# "SELECT name from employee where id = $1"
postgres-# LANGUAGE "sql";
CREATE FUNCTION
postgres=#
postgres=#
postgres=# select * from title(1);
 title
-------
 Jason
(1 row)
postgres=#
postgres=#
postgres=# drop table employee;
DROP TABLE
postgres=#

Functions with Output Parameters

postgres=#
postgres=# -- Functions with Output Parameters
postgres=#
postgres=# CREATE FUNCTION add_em (IN x int, IN y int, OUT sum int)
postgres-# AS "SELECT $1 + $2"
postgres-# LANGUAGE SQL;
CREATE FUNCTION
postgres=#
postgres=# SELECT add_em(3,7);
 REATE
 add_em
--------
     10
(1 row)
postgres=#
postgres=# drop function add_em(IN x int, IN y int, OUT sum int);
DROP FUNCTION
postgres=#
postgres=#

Pass in entire table row to a function

postgres=#
postgres=# CREATE TABLE emp (
postgres(#    name        text,
postgres(#    salary      numeric,
postgres(#    age         integer,
postgres(#    cubicle     point
postgres(# );
CREATE TABLE
postgres=#
postgres=#
postgres=# CREATE FUNCTION getname(emp) RETURNS text AS $$
postgres$#    SELECT $1.name;
postgres$# $$ LANGUAGE SQL;
CREATE FUNCTION
postgres=#
postgres=# SELECT getname(emp.*) from emp;
  REATE
 getname
---------
(0 rows)
postgres=#
postgres=# drop function getname(emp);
DROP FUNCTION
postgres=# drop table emp;
DROP TABLE
postgres=#
postgres=#

The simplest possible SQL function has no arguments and simply returns a base type

postgres=#
postgres=# -- The simplest possible SQL function has no arguments and simply returns a base type
postgres=#
postgres=# CREATE FUNCTION one() RETURNS integer AS $$
postgres$#    SELECT 1 AS result;
postgres$# $$ LANGUAGE SQL;
CREATE FUNCTION
postgres=#
postgres=# select one();
 one
-----
   1
(1 row)
postgres=#
postgres=# drop function one();
DROP FUNCTION
postgres=#
postgres=#