в 13:45, 26 мая 2010

2010-05-26T13:45:56Z

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2010-05-26T10:14:38Z

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=="Anyelement" parameter==



<source lang="sql">

postgres=#
postgres=# CREATE FUNCTION is_greater(anyelement, anyelement) RETURNS boolean AS $$
postgres$# SELECT $1 > $2;
postgres$# $$ LANGUAGE SQL;
CREATE FUNCTION
postgres=#
postgres=# SELECT is_greater(1, 2);
REATE
is_greater
------------
f
(1 row)
postgres=#
postgres=# drop function is_greater(anyelement, anyelement);
DROP FUNCTION
postgres=#
postgres=#

</source>

==Here the $1 references the value of the first function argument whenever the function is invoked==



<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=# CREATE FUNCTION myFunction(text) RETURNS employee
postgres-# AS $$ SELECT * FROM employee WHERE name = $1 $$
postgres-# LANGUAGE SQL;
CREATE FUNCTION
postgres=#
postgres=# -- Here the $1 references the value of the first function argument whenever the function is invoked.
postgres=#
postgres=#
postgres=# select * from myFunction("James");
id | name | salary | start_date | city | region
----+-------+--------+------------+---------+--------
6 | James | 70060 | 1999-09-06 | Toronto | N
(1 row)
postgres=#
postgres=#
postgres=# drop function myFunction(text);
DROP FUNCTION
postgres=# drop table employee;
DROP TABLE
postgres=#
postgres=#

</source>

==OUT parameter==



<source lang="sql">

postgres=#
postgres=#
postgres=# CREATE FUNCTION sales_tax(subtotal real, OUT tax real) AS $$
postgres$# BEGIN
postgres$# tax := subtotal * 0.06;
postgres$# END;
postgres$# $$ LANGUAGE plpgsql;
postgres=#
postgres=# select sales_tax(100);
REATE
sales_tax
-----------
6
(1 row)
postgres=#
postgres=# drop function sales_tax(subtotal real, OUT tax real);
DROP FUNCTION
postgres=#
postgres=#

</source>

==Output parameters are most useful when returning multiple values==



<source lang="sql">

postgres=#
postgres=# -- Output parameters are most useful when returning multiple values
postgres=#
postgres=# CREATE FUNCTION sum_n_product(x int, y int, OUT sum int, OUT prod int) AS $$
postgres$# BEGIN
postgres$# sum := x + y;
postgres$# prod := x * y;
postgres$# END;
postgres$# $$ LANGUAGE plpgsql;
CREATE FUNCTION
postgres=#
postgres=# select sum_n_product(1,2);
REATE
sum_n_product
---------------
(3,2)
(1 row)
postgres=#
postgres=# drop function sum_n_product(x int, y int, OUT sum int, OUT prod int);
DROP FUNCTION
postgres=#
postgres=#

</source>

==Pass constant to function==



<source lang="sql">
postgres=#
postgres=# CREATE FUNCTION "you_me" (integer) RETURNS integer AS "
postgres"# DECLARE
postgres"# RENAME $1 TO user_no;
postgres"# --you INTEGER := 5;
postgres"# BEGIN
postgres"# return user_no;
postgres"# END;" LANGUAGE "plpgsql";
CREATE FUNCTION
postgres=#
postgres=# select you_me(1);
you_me
--------
1
(1 row)
postgres=#

</source>

==Pass in a whole row==



<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;
REATE
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=# CREATE FUNCTION concat_selected_fields(in_t employee) RETURNS text AS $$
postgres$# BEGIN
postgres$# RETURN in_t.ID || in_t.name || in_t.city || in_t.region;
postgres$# END;
postgres$# $$ LANGUAGE plpgsql;
CREATE FUNCTION
postgres=#
postgres=# select concat_selected_fields(employee.*) from employee;
REATE
concat_selected_fields
------------------------
1JasonNew YorkW
2RobertVancouverN
3CeliaTorontoW
4LindaNew YorkN
5DavidVancouverW
6JamesTorontoN
7AlisonNew YorkW
8ChrisVancouverN
9MaryTorontoW
(9 rows)
postgres=#
postgres=#
postgres=# drop function concat_selected_fields(in_t employee);
DROP FUNCTION
postgres=# drop table employee;
DROP TABLE
postgres=#
postgres=#

</source>

==Real number parameter==



<source lang="sql">
postgres=#
postgres=#
postgres=#
postgres=# CREATE FUNCTION sales_tax(subtotal real) RETURNS real AS $$
postgres$# BEGIN
postgres$# RETURN subtotal * 0.06;
postgres$# END;
postgres$# $$ LANGUAGE plpgsql;
postgres=#
postgres=#
postgres=# select sales_tax(100);
REATE
sales_tax
-----------
6
(1 row)
postgres=#
postgres=# drop function sales_tax( real);
DROP FUNCTION
postgres=#
postgres=#

</source>

==Two out parameters==



<source lang="sql">

postgres=#
postgres=# CREATE FUNCTION dup (f1 anyelement, OUT f2 anyelement, OUT f3 anyarray)
postgres-# AS "select $1, array[$1,$1]" LANGUAGE sql;
CREATE FUNCTION
postgres=#
postgres=# SELECT * FROM dup(22);
REATE
f2 | f3
----+---------
22 | {22,22}
(1 row)
postgres=#
postgres=# drop function dup(f1 anyelement, OUT f2 anyelement, OUT f3 anyarray);
postgres=#
postgres=#

</source>

==Use defined data type as the function parameter==



<source lang="sql">
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=#
postgres=# CREATE FUNCTION price_extension(inventory_item, integer) RETURNS numeric
postgres-# AS "SELECT $1.price * $2" LANGUAGE SQL;
CREATE FUNCTION
postgres=#
postgres=# select price_extension(ROW("fuzzy dice", 42, 1.99), 1000);
price_extension
-----------------
1990.00
(1 row)
postgres=#
postgres=# drop function price_extension(inventory_item, integer);
DROP FUNCTION
postgres=# drop table on_hand;
DROP TABLE
postgres=# drop type inventory_item;
DROP TYPE
postgres=#
postgres=#

</source>

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PostgreSQL/Store Procedure Function/Function Parameter - История изменений

в 13:45, 26 мая 2010

Admin: 1 версия