PostgreSQL/Aggregate Functions/Min

Use min function in table 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=#
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 min(retail), p.name
postgres-#         FROM (stock NATURAL JOIN editions)
postgres-#         JOIN publishers AS p (publisher_id)
postgres-#                         USING (publisher_id)
postgres-#         GROUP BY p.name
postgres-#         ORDER BY min ASC;
  min  |    name
-------+------------
 16.95 | R Inc
 21.95 | A Inc
 21.95 | B
 22.95 | Z Inc
 23.95 | Can Press
 23.95 | Henry Inc.
 24.95 | M Press
 24.95 | P Inc
 28.95 | D Inc
 28.95 | H Pubs
 28.95 | W Pubs
(11 rows)
postgres=#
postgres=# drop table publishers;
DROP TABLE
postgres=# drop table editions;
DROP TABLE
postgres=#