PostgreSQL/Analytical Functions/stddev — различия между версиями
Admin (обсуждение | вклад) м (1 версия) |
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(нет различий)
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Версия 13:45, 26 мая 2010
stddev function demo
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=#
stddev with natural join
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=#