Using variance function with natural join : Variance « Analytical Functions « PostgreSQL






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=#
           
       








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