PostgreSQL/Sequence/Sequence Value
Содержание
Get next sequence value
<source lang="sql">
postgres=# -- Creation of a sequence postgres=# postgres=# CREATE SEQUENCE shipments_ship_id_seq START 200 INCREMENT 1; CREATE SEQUENCE postgres=# postgres=# -- Select the next number from a sequence with the nextval() function: postgres=# postgres=# SELECT nextval ("shipments_ship_id_seq");
nextval
200
(1 row) postgres=# postgres=# postgres=# drop sequence shipments_ship_id_seq; DROP SEQUENCE postgres=#
</source>
Get sequence last value and increment_by
<source lang="sql">
postgres=# CREATE SEQUENCE myseq MINVALUE 0; CREATE SEQUENCE postgres=# postgres=# SELECT last_value, increment_by FROM myseq;
last_value | increment_by
+--------------
0 | 1
(1 row) postgres=# postgres=# drop sequence myseq; DROP SEQUENCE postgres=#
</source>
Get sequence next value
<source lang="sql">
postgres=# CREATE SEQUENCE myseq MINVALUE 0; CREATE SEQUENCE postgres=# -- Incrementing a sequence postgres=# postgres=# SELECT nextval("myseq");
nextval
0
(1 row) postgres=# postgres=# SELECT nextval("myseq");
nextval
1
(1 row) postgres=# postgres=# drop sequence myseq; DROP SEQUENCE postgres=#
</source>
Reference sequence value in insert statement
<source lang="sql">
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=# -- Creation of a sequence postgres=# postgres=# CREATE SEQUENCE myseq START 200 INCREMENT 1; CREATE SEQUENCE postgres=# postgres=# INSERT INTO employee (id)VALUES (nextval("myseq")); 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 200 | | | | |
(10 rows) postgres=# postgres=# drop sequence myseq; DROP SEQUENCE postgres=# drop table employee; DROP TABLE postgres=# postgres=#
</source>
Reference sequence value in table creation statement
<source lang="sql">
postgres=# -- Creation of a sequence postgres=# postgres=# CREATE SEQUENCE myseq START 200 INCREMENT 1; CREATE SEQUENCE postgres=# postgres=# CREATE TABLE shipments ( postgres(# id integer NOT NULL DEFAULT nextval("myseq"), postgres(# customer_id integer, postgres(# isbn text, postgres(# ship_date timestamp); CREATE TABLE postgres=# postgres=# postgres=# drop table shipments; DROP TABLE postgres=# drop sequence myseq; DROP SEQUENCE postgres=#
</source>