PostgreSQL/Table/Add Column

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Add a column

   <source lang="sql">

postgres=# postgres=# -- Creating the books table postgres=# postgres=# CREATE TABLE books ( postgres(# id integer UNIQUE, postgres(# title text NOT NULL, postgres(# author_id integer, postgres(# subject_id integer, postgres(# CONSTRAINT books_id_pkey PRIMARY KEY (id)); NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "books_id_pkey" for table "books" CREATE TABLE postgres=# postgres=# \d books; 

      Table "public.books"
  Column   |  Type   | Modifiers
+---------+----------- 
id         | integer | not null
title      | text    | not null
author_id  | integer |
subject_id | integer |

Indexes: 

   "books_id_pkey" PRIMARY KEY, btree (id)

postgres=# postgres=# -- Adding a column postgres=# postgres=# ALTER TABLE books ADD publication date; ALTER TABLE postgres=# postgres=# postgres=# \d books; 

      Table "public.books"
  Column    |  Type   | Modifiers
+---------+----------- 
id          | integer | not null
title       | text    | not null
author_id   | integer |
subject_id  | integer |
publication | date    |

Indexes: 

   "books_id_pkey" PRIMARY KEY, btree (id)

postgres=# postgres=# drop table books; DROP TABLE postgres=# postgres=# 

      </source>


Add a new column with check option

   <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=# ALTER TABLE employee ADD COLUMN description text CHECK (description <> ""); ALTER TABLE postgres=# postgres=# select * from employee; 

id |  name  | salary | start_date |   city    | region | description
+--------+--------+------------+-----------+--------+------------- 
 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=# \d employee; 

            Table "public.employee"
  Column    |         Type          | Modifiers
+-----------------------+----------- 
id          | integer               |
name        | character varying(10) |
salary      | real                  |
start_date  | date                  |
city        | character varying(10) |
region      | character(1)          |
description | text                  |

Check constraints: 

   "employee_description_check" CHECK (description <> ""::text)

postgres=# postgres=# drop table employee; DROP TABLE postgres=# postgres=# 

      </source>


Adds a text column

   <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=# -- Adds a text column postgres=# ALTER TABLE employee ADD COLUMN address text; ALTER TABLE postgres=# postgres=# select * from employee; 

id |  name  | salary | start_date |   city    | region | address
+--------+--------+------------+-----------+--------+--------- 
 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=# drop table employee; DROP TABLE postgres=# postgres=# 

      </source>


Altering column defaults

   <source lang="sql">

postgres=# postgres=# -- Creating the books table postgres=# postgres=# CREATE TABLE books ( postgres(# id integer UNIQUE, postgres(# title text NOT NULL, postgres(# author_id integer, postgres(# subject_id integer, postgres(# CONSTRAINT books_id_pkey PRIMARY KEY (id)); NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "books_id_pkey" for table "books" CREATE TABLE postgres=# postgres=# \d books; 

      Table "public.books"
  Column   |  Type   | Modifiers
+---------+----------- 
id         | integer | not null
title      | text    | not null
author_id  | integer |
subject_id | integer |

Indexes: 

   "books_id_pkey" PRIMARY KEY, btree (id)

postgres=# postgres=# postgres=# -- Altering column defaults postgres=# postgres=# ALTER TABLE books ALTER COLUMN id SET DEFAULT nextval("book_ids"); ERROR: relation "book_ids" does not exist postgres=# postgres=# \d books; 

      Table "public.books"
  Column   |  Type   | Modifiers
+---------+----------- 
id         | integer | not null
title      | text    | not null
author_id  | integer |
subject_id | integer |

Indexes: 

   "books_id_pkey" PRIMARY KEY, btree (id)

postgres=# postgres=# drop table books; DROP TABLE postgres=# 

      </source>


ALTER TABLE employee ADD COLUMN description text

   <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=# ALTER TABLE employee ADD COLUMN description text; ALTER TABLE postgres=# postgres=# select * from employee; 

id |  name  | salary | start_date |   city    | region | description
+--------+--------+------------+-----------+--------+------------- 
 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=# \d employee; 

            Table "public.employee"
  Column    |         Type          | Modifiers
+-----------------------+----------- 
id          | integer               |
name        | character varying(10) |
salary      | real                  |
start_date  | date                  |
city        | character varying(10) |
region      | character(1)          |
description | text                  |

postgres=# postgres=# drop table employee; DROP TABLE postgres=# postgres=# 

      </source>
Источник — «http://sqle.ru/index.php?title=PostgreSQL/Table/Add_Column&oldid=4649»