PostgreSQL/Table Joins/INNER JOIN
Содержание
Comparing INNER JOIN to WHERE
postgres=#
postgres=# CREATE TABLE "books" (
postgres(# "id" integer NOT NULL,
postgres(# "title" text NOT NULL,
postgres(# "author_id" integer,
postgres(# "subject_id" integer,
postgres(# Constraint "books_id_pkey" Primary Key ("id")
postgres(# );
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "books_id_pkey" for table "books"
CREATE TABLE
postgres=#
postgres=#
postgres=# insert into books values (7808, "Java", 4156, 9);
INSERT 0 1
postgres=# insert into books values (4513, "Javascript", 1866, 15);
INSERT 0 1
postgres=# insert into books values (4267, "C#", 2001, 15);
INSERT 0 1
postgres=# insert into books values (1608, "Oracle", 1809, 2);
INSERT 0 1
postgres=# insert into books values (1590, "Sql Server", 1809, 2);
INSERT 0 1
postgres=# insert into books values (25908, "Postgre SQL", 15990, 2);
INSERT 0 1
postgres=# insert into books values (1501, "Python", 2031, 2);
INSERT 0 1
postgres=# insert into books values (190, "Java by API", 16, 6);
INSERT 0 1
postgres=# insert into books values (1234, "2D", 25041, 3);
INSERT 0 1
postgres=# insert into books values (2038, "C", 1644, 0);
INSERT 0 1
postgres=# insert into books values (156, "C++", 115, 9);
INSERT 0 1
postgres=# insert into books values (41473, "Programming Python", 7805, 4);
INSERT 0 1
postgres=# insert into books values (41477, "Learning Python", 7805, 4);
INSERT 0 1
postgres=# insert into books values (41478, "Perl Cookbook", 7806, 4);
INSERT 0 1
postgres=# insert into books values (41472, "Practical PostgreSQL", 1212, 4);
INSERT 0 1
postgres=#
postgres=# select * from books;
id | title | author_id | subject_id
-------+----------------------+-----------+------------
7808 | Java | 4156 | 9
4513 | Javascript | 1866 | 15
4267 | C# | 2001 | 15
1608 | Oracle | 1809 | 2
1590 | Sql Server | 1809 | 2
25908 | Postgre SQL | 15990 | 2
1501 | Python | 2031 | 2
190 | Java by API | 16 | 6
1234 | 2D | 25041 | 3
2038 | C | 1644 | 0
156 | C++ | 115 | 9
41473 | Programming Python | 7805 | 4
41477 | Learning Python | 7805 | 4
41478 | Perl Cookbook | 7806 | 4
41472 | Practical PostgreSQL | 1212 | 4
(15 rows)
postgres=#
postgres=# CREATE TABLE "authors" (
postgres(# "id" integer NOT NULL,
postgres(# "last_name" text,
postgres(# "first_name" text,
postgres(# Constraint "authors_pkey" Primary Key ("id")
postgres(# );
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "authors_pkey" for table "authors"
CREATE TABLE
postgres=#
postgres=#
postgres=# insert into authors values (1111, "Martin", "Jason");
INSERT 0 1
postgres=# insert into authors values (1212, "Worsley", "Robert");
INSERT 0 1
postgres=# insert into authors values (15990, "Mathews", "John");
INSERT 0 1
postgres=# insert into authors values (25041, "Smith", "Williams");
INSERT 0 1
postgres=# insert into authors values (16, "Alcott", "May");
INSERT 0 1
postgres=# insert into authors values (4156, "King", "Stephen");
INSERT 0 1
postgres=# insert into authors values (1866, "Herbert", "Margaret");
INSERT 0 1
postgres=# insert into authors values (1644, "Hogarth", "Celia");
INSERT 0 1
postgres=# insert into authors values (2031, "Brown", "Wise");
INSERT 0 1
postgres=# insert into authors values (115, "Poe", "Allen");
INSERT 0 1
postgres=# insert into authors values (7805, "Lutz", "Mark");
INSERT 0 1
postgres=# insert into authors values (7806, "Rice", "Tom");
INSERT 0 1
postgres=# insert into authors values (1533, "Black", "Chris");
INSERT 0 1
postgres=# insert into authors values (1717, "Brite", "Linda");
INSERT 0 1
postgres=# insert into authors values (2112, "Larry", "Edward");
INSERT 0 1
postgres=# insert into authors values (2001, "Clarke", "Alison");
INSERT 0 1
postgres=# insert into authors values (1213, "Green", "Mary");
INSERT 0 1
postgres=#
postgres=# select * from authors;
id | last_name | first_name
-------+-----------+------------
1111 | Martin | Jason
1212 | Worsley | Robert
15990 | Mathews | John
25041 | Smith | Williams
16 | Alcott | May
4156 | King | Stephen
1866 | Herbert | Margaret
1644 | Hogarth | Celia
2031 | Brown | Wise
115 | Poe | Allen
7805 | Lutz | Mark
7806 | Rice | Tom
1533 | Black | Chris
1717 | Brite | Linda
2112 | Larry | Edward
2001 | Clarke | Alison
1213 | Green | Mary
(17 rows)
postgres=#
postgres=# -- Comparing INNER JOIN to WHERE
postgres=#
postgres=# SELECT title, last_name, first_name
postgres-# FROM books, authors
postgres-# WHERE (books.author_id = authors.id)
postgres-# AND last_name = "Geisel";
title | last_name | first_name
-------+-----------+------------
(0 rows)
postgres=#
postgres=#
postgres=#
postgres=#
postgres=# drop table authors;
DROP TABLE
postgres=# drop table books;
DROP TABLE
postgres=#
postgres=#
INNER JOIN two tables
postgres=#
postgres=# CREATE TABLE "books" (
postgres(# "id" integer NOT NULL,
postgres(# "title" text NOT NULL,
postgres(# "author_id" integer,
postgres(# "subject_id" integer,
postgres(# Constraint "books_id_pkey" Primary Key ("id")
postgres(# );
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "books_id_pkey" for table "books"
CREATE TABLE
postgres=#
postgres=#
postgres=# insert into books values (7808, "Java", 4156, 9);
INSERT 0 1
postgres=# insert into books values (4513, "Javascript", 1866, 15);
INSERT 0 1
postgres=# insert into books values (4267, "C#", 2001, 15);
INSERT 0 1
postgres=# insert into books values (1608, "Oracle", 1809, 2);
INSERT 0 1
postgres=# insert into books values (1590, "Sql Server", 1809, 2);
INSERT 0 1
postgres=# insert into books values (25908, "Postgre SQL", 15990, 2);
INSERT 0 1
postgres=# insert into books values (1501, "Python", 2031, 2);
INSERT 0 1
postgres=# insert into books values (190, "Java by API", 16, 6);
INSERT 0 1
postgres=# insert into books values (1234, "2D", 25041, 3);
INSERT 0 1
postgres=# insert into books values (2038, "C", 1644, 0);
INSERT 0 1
postgres=# insert into books values (156, "C++", 115, 9);
INSERT 0 1
postgres=# insert into books values (41473, "Programming Python", 7805, 4);
INSERT 0 1
postgres=# insert into books values (41477, "Learning Python", 7805, 4);
INSERT 0 1
postgres=# insert into books values (41478, "Perl Cookbook", 7806, 4);
INSERT 0 1
postgres=# insert into books values (41472, "Practical PostgreSQL", 1212, 4);
INSERT 0 1
postgres=#
postgres=# select * from books;
id | title | author_id | subject_id
-------+----------------------+-----------+------------
7808 | Java | 4156 | 9
4513 | Javascript | 1866 | 15
4267 | C# | 2001 | 15
1608 | Oracle | 1809 | 2
1590 | Sql Server | 1809 | 2
25908 | Postgre SQL | 15990 | 2
1501 | Python | 2031 | 2
190 | Java by API | 16 | 6
1234 | 2D | 25041 | 3
2038 | C | 1644 | 0
156 | C++ | 115 | 9
41473 | Programming Python | 7805 | 4
41477 | Learning Python | 7805 | 4
41478 | Perl Cookbook | 7806 | 4
41472 | Practical PostgreSQL | 1212 | 4
(15 rows)
postgres=#
postgres=# CREATE TABLE "authors" (
postgres(# "id" integer NOT NULL,
postgres(# "last_name" text,
postgres(# "first_name" text,
postgres(# Constraint "authors_pkey" Primary Key ("id")
postgres(# );
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "authors_pkey" for table "authors"
CREATE TABLE
postgres=#
postgres=#
postgres=# insert into authors values (1111, "Martin", "Jason");
INSERT 0 1
postgres=# insert into authors values (1212, "Worsley", "Robert");
INSERT 0 1
postgres=# insert into authors values (15990, "Mathews", "John");
INSERT 0 1
postgres=# insert into authors values (25041, "Smith", "Williams");
INSERT 0 1
postgres=# insert into authors values (16, "Alcott", "May");
INSERT 0 1
postgres=# insert into authors values (4156, "King", "Stephen");
INSERT 0 1
postgres=# insert into authors values (1866, "Herbert", "Margaret");
INSERT 0 1
postgres=# insert into authors values (1644, "Hogarth", "Celia");
INSERT 0 1
postgres=# insert into authors values (2031, "Brown", "Wise");
INSERT 0 1
postgres=# insert into authors values (115, "Poe", "Allen");
INSERT 0 1
postgres=# insert into authors values (7805, "Lutz", "Mark");
INSERT 0 1
postgres=# insert into authors values (7806, "Rice", "Tom");
INSERT 0 1
postgres=# insert into authors values (1533, "Black", "Chris");
INSERT 0 1
postgres=# insert into authors values (1717, "Brite", "Linda");
INSERT 0 1
postgres=# insert into authors values (2112, "Larry", "Edward");
INSERT 0 1
postgres=# insert into authors values (2001, "Clarke", "Alison");
INSERT 0 1
postgres=#
postgres=# select * from authors;
id | last_name | first_name
-------+-----------+------------
1111 | Martin | Jason
1212 | Worsley | Robert
15990 | Mathews | John
25041 | Smith | Williams
16 | Alcott | May
4156 | King | Stephen
1866 | Herbert | Margaret
1644 | Hogarth | Celia
2031 | Brown | Wise
115 | Poe | Allen
7805 | Lutz | Mark
7806 | Rice | Tom
1533 | Black | Chris
1717 | Brite | Linda
2112 | Larry | Edward
2001 | Clarke | Alison
(16 rows)
postgres=#
postgres=# SELECT title, last_name, first_name
postgres-# FROM books AS b INNER JOIN authors AS a
postgres-# ON (b.author_id = a.id)
postgres-# WHERE last_name = "Green";
title | last_name | first_name
-------+-----------+------------
(0 rows)
postgres=#
postgres=#
postgres=#
postgres=#
postgres=# drop table authors;
DROP TABLE
postgres=# drop table books;
DROP TABLE
postgres=#
postgres=#
INNER JOIN two tables (2)
postgres=#
postgres=# CREATE TABLE t1 (
postgres(# num int,
postgres(# name varchar(10)
postgres(# );
CREATE TABLE
postgres=#
postgres=# insert into t1 values(1,"a");
INSERT 0 1
postgres=# insert into t1 values(2,"b");
INSERT 0 1
postgres=# insert into t1 values(3,"c");
INSERT 0 1
postgres=#
postgres=# CREATE TABLE t2 (
postgres(# num int,
postgres(# name varchar(10)
postgres(# );
CREATE TABLE
postgres=#
postgres=# insert into t2 values(1,"xxx");
INSERT 0 1
postgres=# insert into t2 values(3,"yyy");
INSERT 0 1
postgres=# insert into t2 values(5,"zzz");
INSERT 0 1
postgres=#
postgres=# SELECT * FROM t1 INNER JOIN t2 ON t1.num = t2.num;
num | name | num | name
-----+------+-----+------
1 | a | 1 | xxx
3 | c | 3 | yyy
(2 rows)
postgres=#
postgres=# drop table t1;
DROP TABLE
postgres=# drop table t2;
DROP TABLE
postgres=#
INNER JOIN two tables USING (a column)
postgres=#
postgres=#
postgres=# CREATE TABLE t1 (
postgres(# num int,
postgres(# name varchar(10)
postgres(# );
CREATE TABLE
postgres=#
postgres=# insert into t1 values(1,"a");
INSERT 0 1
postgres=# insert into t1 values(2,"b");
INSERT 0 1
postgres=# insert into t1 values(3,"c");
INSERT 0 1
postgres=#
postgres=# CREATE TABLE t2 (
postgres(# num int,
postgres(# name varchar(10)
postgres(# );
CREATE TABLE
postgres=#
postgres=# insert into t2 values(1,"xxx");
INSERT 0 1
postgres=# insert into t2 values(3,"yyy");
INSERT 0 1
postgres=# insert into t2 values(5,"zzz");
INSERT 0 1
postgres=#
postgres=# SELECT * FROM t1 INNER JOIN t2 USING (num);
num | name | name
-----+------+------
1 | a | xxx
3 | c | yyy
(2 rows)
postgres=#
postgres=# drop table t1;
DROP TABLE
postgres=# drop table t2;
DROP TABLE
postgres=#
Using GROUP BY with inner join
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(# CONSTRAINT "integrity" CHECK (((book_id NOTNULL) AND (edition NOTNULL))),
postgres(# Constraint "pkey" Primary Key ("isbn")
postgres(# );
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "pkey" for table "editions"
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=#
postgres=# --Using GROUP BY
postgres=#
postgres=# SELECT count(e.isbn) AS "number of books",
postgres-# p.name AS publisher
postgres-# FROM editions AS e INNER JOIN publishers AS p
postgres-# ON (e.publisher_id = p.id)
postgres-# GROUP BY p.name;
number of books | publisher
-----------------+------------
1 | B
2 | D Inc
1 | O Inc.
2 | A Inc
1 | H Pubs
1 | W Pubs
1 | P Inc
2 | Z Inc
1 | Can Press
3 | R Inc
1 | M Press
1 | Henry Inc.
(12 rows)
postgres=#
postgres=# drop table editions cascade;
DROP TABLE
postgres=# drop table publisher cascade;
ERROR: table "publisher" does not exist
postgres=#