PostgreSQL/Analytical Functions/stddev — различия между версиями
Admin (обсуждение | вклад) м (1 версия) |
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(нет различий)
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Версия 16:45, 26 мая 2010
stddev function demo
<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=# SELECT stddev(salary) FROM employee;
stddev
26805.9333730426
(1 row) postgres=# postgres=# postgres=# drop table employee; DROP TABLE postgres=#
</source>
stddev with natural join
<source lang="sql">
postgres=# postgres=# postgres=# CREATE TABLE "editions" ( postgres(# "isbn" text NOT NULL, postgres(# "book_id" integer, postgres(# "edition" integer, postgres(# "publisher_id" integer, postgres(# "publication" date, postgres(# "type" character(1) postgres(# ); CREATE TABLE postgres=# postgres=# insert into editions values("039480001X", 1608, 1, 59, "1957-03-01", "h"); INSERT 0 1 postgres=# insert into editions values("0451160916", 7808, 1, 75, "1981-08-01", "p"); INSERT 0 1 postgres=# insert into editions values("0394800753", 1590, 1, 59, "1949-03-01", "p"); INSERT 0 1 postgres=# insert into editions values("0590445065", 25908, 1, 150, "1987-03-01", "p"); INSERT 0 1 postgres=# insert into editions values("0694003611", 1501, 1, 65, "1947-03-04", "p"); INSERT 0 1 postgres=# insert into editions values("0679803335", 1234, 1, 102, "1922-01-01", "p"); INSERT 0 1 postgres=# insert into editions values("0760720002", 190, 1, 91, "1868-01-01", "p"); INSERT 0 1 postgres=# insert into editions values("0394900014", 1608, 1, 59, "1957-01-01", "p"); INSERT 0 1 postgres=# insert into editions values("0385121679", 7808, 2, 75, "1993-10-01", "h"); INSERT 0 1 postgres=# insert into editions values("1885418035", 156, 1, 163, "1995-03-28", "p"); INSERT 0 1 postgres=# insert into editions values("0929605942", 156, 2, 171, "1998-12-01", "p"); INSERT 0 1 postgres=# insert into editions values("0441172717", 4513, 2, 99, "1998-09-01", "p"); INSERT 0 1 postgres=# insert into editions values("044100590X", 4513, 3, 99, "1999-10-01", "h"); INSERT 0 1 postgres=# insert into editions values("0451457994", 4267, 3, 101, "2000-09-12", "p"); INSERT 0 1 postgres=# insert into editions values("0451198492", 4267, 3, 101, "1999-10-01", "h"); INSERT 0 1 postgres=# insert into editions values("0823015505", 2038, 1, 62, "1958-01-01", "p"); INSERT 0 1 postgres=# insert into editions values("0596000855", 41473, 2, 113, "2001-03-01", "p"); INSERT 0 1 postgres=# postgres=# select * from editions;
isbn | book_id | edition | publisher_id | publication | type
+---------+---------+--------------+-------------+------
039480001X | 1608 | 1 | 59 | 1957-03-01 | h 0451160916 | 7808 | 1 | 75 | 1981-08-01 | p 0394800753 | 1590 | 1 | 59 | 1949-03-01 | p 0590445065 | 25908 | 1 | 150 | 1987-03-01 | p 0694003611 | 1501 | 1 | 65 | 1947-03-04 | p 0679803335 | 1234 | 1 | 102 | 1922-01-01 | p 0760720002 | 190 | 1 | 91 | 1868-01-01 | p 0394900014 | 1608 | 1 | 59 | 1957-01-01 | p 0385121679 | 7808 | 2 | 75 | 1993-10-01 | h 1885418035 | 156 | 1 | 163 | 1995-03-28 | p 0929605942 | 156 | 2 | 171 | 1998-12-01 | p 0441172717 | 4513 | 2 | 99 | 1998-09-01 | p 044100590X | 4513 | 3 | 99 | 1999-10-01 | h 0451457994 | 4267 | 3 | 101 | 2000-09-12 | p 0451198492 | 4267 | 3 | 101 | 1999-10-01 | h 0823015505 | 2038 | 1 | 62 | 1958-01-01 | p 0596000855 | 41473 | 2 | 113 | 2001-03-01 | p
(17 rows) postgres=# postgres=# postgres=# CREATE TABLE "publishers" ( postgres(# "id" integer NOT NULL, postgres(# "name" text, postgres(# "address" text, postgres(# Constraint "publishers_pkey" Primary Key ("id") postgres(# ); NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "publishers_pkey" for table "publishers" CREATE TABLE postgres=# postgres=# postgres=# insert into publishers values(150, "Can Press", "29 Ave. Toronto, ON"); INSERT 0 1 postgres=# insert into publishers values(91, "Henry Inc.", "115 Street New York, NY"); INSERT 0 1 postgres=# insert into publishers values(113, "O Inc.", "101 St, Sebastopol, CA"); INSERT 0 1 postgres=# insert into publishers values(62, "W Pubs", "1515, New York"); INSERT 0 1 postgres=# insert into publishers values(105, "N Press", "19 W, New York"); INSERT 0 1 postgres=# insert into publishers values(99, "A Inc", "375 St, New York"); INSERT 0 1 postgres=# insert into publishers values(101, "Z Inc", "375 Ave, New York"); INSERT 0 1 postgres=# insert into publishers values(163, "M Press", "PO Box 1215"); INSERT 0 1 postgres=# insert into publishers values(171, "B", "16 W. 18th St. New York"); INSERT 0 1 postgres=# insert into publishers values(102, "P Inc", "375 Hudson St, New York"); INSERT 0 1 postgres=# insert into publishers values(75, "D Inc", "1540 Broadway, New York"); INSERT 0 1 postgres=# insert into publishers values(65, "H Pubs", "10 E 53rd St, New York"); INSERT 0 1 postgres=# insert into publishers values(59, "R Inc", "1540 Broadway, New York"); INSERT 0 1 postgres=# postgres=# select * from publishers;
id | name | address
+------------+-------------------------
150 | Can Press | 29 Ave. Toronto, ON 91 | Henry Inc. | 115 Street New York, NY 113 | O Inc. | 101 St, Sebastopol, CA 62 | W Pubs | 1515, New York 105 | N Press | 19 W, New York 99 | A Inc | 375 St, New York 101 | Z Inc | 375 Ave, New York 163 | M Press | PO Box 1215 171 | B | 16 W. 18th St. New York 102 | P Inc | 375 Hudson St, New York 75 | D Inc | 1540 Broadway, New York 65 | H Pubs | 10 E 53rd St, New York 59 | R Inc | 1540 Broadway, New York
(13 rows) postgres=# postgres=# SELECT stddev(retail), p.name postgres-# FROM (stock NATURAL JOIN editions) postgres-# JOIN publishers AS p ON (publisher_id = p.id) postgres-# GROUP BY p.name postgres-# ORDER BY stddev DESC postgres-# LIMIT 4;
stddev | name
+-----------
| B
| M Press
| Can Press
| H Pubs
(4 rows) postgres=# postgres=# drop table publishers; DROP TABLE postgres=# drop table editions; DROP TABLE postgres=#
</source>
