PostgreSQL/Select Query/Order
Содержание
Order by in ascending order
<source lang="sql">
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=# postgres=# SELECT DISTINCT ON (substr) name, substr(name, 1, 1), ascii(name) postgres-# FROM employee postgres-# ORDER BY substr ASC;
name | substr | ascii
+--------+-------
Alison | A | 65 Celia | C | 67 David | D | 68 Jason | J | 74 Linda | L | 76 Mary | M | 77 Robert | R | 82
(7 rows) postgres=# postgres=# drop table employee; DROP TABLE postgres=#
</source>
Using DISTINCT and ORDER BY together
<source lang="sql">
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=# -- Using DISTINCT and ORDER BY together postgres=# postgres=# SELECT DISTINCT city postgres-# FROM employee postgres-# ORDER BY city;
city
New York Toronto Vancouver
(3 rows) postgres=# postgres=# drop table employee; DROP TABLE postgres=# postgres=#
</source>
Using DISTINCT with ORDER BY
<source lang="sql">
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=# 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
(6 rows) postgres=# postgres=# -- Using DISTINCT with ORDER BY postgres=# postgres=# SELECT DISTINCT ON (edition) postgres-# edition, publication postgres-# FROM editions postgres-# ORDER BY edition ASC, postgres-# publication DESC;
edition | publication
+-------------
1 | 1987-03-01
(1 row) postgres=# postgres=# postgres=# postgres=# drop table editions; DROP TABLE postgres=# postgres=# postgres=#
</source>
Using ORDER BY
<source lang="sql">
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("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 0596000855 | 41473 | 2 | 113 | 2001-03-01 | p
(6 rows) postgres=# postgres=# --Using ORDER BY postgres=# postgres=# SELECT isbn, edition, publication postgres-# FROM editions postgres-# ORDER BY publication ASC;
isbn | edition | publication
+---------+-------------
0694003611 | 1 | 1947-03-04 0394800753 | 1 | 1949-03-01 039480001X | 1 | 1957-03-01 0451160916 | 1 | 1981-08-01 0590445065 | 1 | 1987-03-01 0596000855 | 2 | 2001-03-01
(6 rows) postgres=# postgres=# postgres=# postgres=# drop table editions; DROP TABLE postgres=# postgres=# postgres=#
</source>
Using ORDER BY with multiple expressions
<source lang="sql">
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=# 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
(6 rows) postgres=# postgres=# -- Using ORDER BY with multiple expressions postgres=# postgres=# SELECT edition, publication postgres-# FROM editions postgres-# ORDER BY edition ASC, postgres-# publication DESC;
edition | publication
+-------------
1 | 1987-03-01 1 | 1981-08-01 1 | 1957-03-01 1 | 1949-03-01 1 | 1947-03-04 1 | 1922-01-01
(6 rows) postgres=# postgres=# postgres=# postgres=# drop table editions; DROP TABLE postgres=# postgres=#
</source>