Using variance function with natural join
postgres=#
postgres=#
postgres=#
postgres=# CREATE TABLE "stock" (
postgres(# "isbn" text NOT NULL,
postgres(# "cost" numeric(5,2),
postgres(# "retail" numeric(5,2),
postgres(# "stock" integer,
postgres(# Constraint "stock_pkey" Primary Key ("isbn")
postgres(# );
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "stock_pkey" for table "stock"
CREATE TABLE
postgres=#
postgres=#
postgres=# insert into stock values ('0385121679', 29.00, 36.95, 65);
INSERT 0 1
postgres=# insert into stock values ('039480001X', 30.00, 32.95, 31);
INSERT 0 1
postgres=# insert into stock values ('0394900014', 23.00, 23.95, 0);
INSERT 0 1
postgres=# insert into stock values ('044100590X', 36.00, 45.95, 89);
INSERT 0 1
postgres=# insert into stock values ('0441172717', 17.00, 21.95, 77);
INSERT 0 1
postgres=# insert into stock values ('0451160916', 24.00, 28.95, 22);
INSERT 0 1
postgres=# insert into stock values ('0451198492', 36.00, 46.95, 0);
INSERT 0 1
postgres=# insert into stock values ('0451457994', 17.00, 22.95, 0);
INSERT 0 1
postgres=# insert into stock values ('0590445065', 23.00, 23.95, 10);
INSERT 0 1
postgres=# insert into stock values ('0679803335', 20.00, 24.95, 18);
INSERT 0 1
postgres=# insert into stock values ('0694003611', 25.00, 28.95, 50);
INSERT 0 1
postgres=# insert into stock values ('0760720002', 18.00, 23.95, 28);
INSERT 0 1
postgres=# insert into stock values ('0823015505', 26.00, 28.95, 16);
INSERT 0 1
postgres=# insert into stock values ('0929605942', 19.00, 21.95, 25);
INSERT 0 1
postgres=# insert into stock values ('1885418035', 23.00, 24.95, 77);
INSERT 0 1
postgres=# insert into stock values ('0394800753', 16.00, 16.95, 4);
INSERT 0 1
postgres=#
postgres=# select * FROM stock;
isbn | cost | retail | stock
------------+-------+--------+-------
0385121679 | 29.00 | 36.95 | 65
039480001X | 30.00 | 32.95 | 31
0394900014 | 23.00 | 23.95 | 0
044100590X | 36.00 | 45.95 | 89
0441172717 | 17.00 | 21.95 | 77
0451160916 | 24.00 | 28.95 | 22
0451198492 | 36.00 | 46.95 | 0
0451457994 | 17.00 | 22.95 | 0
0590445065 | 23.00 | 23.95 | 10
0679803335 | 20.00 | 24.95 | 18
0694003611 | 25.00 | 28.95 | 50
0760720002 | 18.00 | 23.95 | 28
0823015505 | 26.00 | 28.95 | 16
0929605942 | 19.00 | 21.95 | 25
1885418035 | 23.00 | 24.95 | 77
0394800753 | 16.00 | 16.95 | 4
(16 rows)
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(# );
postgres=#
postgres=#
postgres=# insert into publishers values(150, 'Can Press', '29 Ave. Toronto, ON');
postgres=# insert into publishers values(91, 'Henry Inc.', '115 Street New York, NY');
postgres=# insert into publishers values(113, 'O Inc.', '101 St, Sebastopol, CA');
postgres=# insert into publishers values(62, 'W Pubs', '1515, New York');
postgres=# insert into publishers values(105, 'N Press', '19 W, New York');
postgres=# insert into publishers values(99, 'A Inc', '375 St, New York');
postgres=# insert into publishers values(101, 'Z Inc', '375 Ave, New York');
postgres=# insert into publishers values(163, 'M Press', 'PO Box 1215');
postgres=# insert into publishers values(171, 'B', '16 W. 18th St. New York');
postgres=# insert into publishers values(102, 'P Inc', '375 Hudson St, New York');
postgres=# insert into publishers values(75, 'D Inc', '1540 Broadway, New York');
postgres=# insert into publishers values(65, 'H Pubs', '10 E 53rd St, New York');
postgres=# insert into publishers values(59, 'R Inc', '1540 Broadway, New York');
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 variance(retail), p.name
postgres-# FROM (stock NATURAL JOIN editions)
postgres-# JOIN publishers AS p
postgres-# ON (editions.publisher_id = p.id)
postgres-# GROUP BY p.name
postgres-# ORDER BY variance DESC
postgres-# LIMIT 4;
variance | name
----------+-----------
| B
| M Press
| Can Press
| H Pubs
(4 rows)
postgres=#
postgres=# drop table publisher;
ERROR: table "publisher" does not exist
postgres=# drop table editions;
DROP TABLE
postgres=# drop table stock;
DROP TABLE
postgres=#
| 1. | Variance function demo |