PostgreSQL/Store Procedure Function/Create Function

Add three parameters together in a function

   <source lang="sql">

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=#

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Case insensitive

   <source lang="sql">

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=#

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Create a simeple function

   <source lang="sql">

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=#

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Functions with Output Parameters

   <source lang="sql">

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=#

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Pass in entire table row to a function

   <source lang="sql">

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=#

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

   <source lang="sql">

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=#

      </source>