CREATE TABLE AS — define a new table from the results of a query
CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ]table_name
[ (column_name
[, ...] ) ] [ USINGmethod
] [ WITH (storage_parameter
[=value
] [, ... ] ) | WITHOUT OIDS ] [ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ] [ TABLESPACEtablespace_name
] ASquery
[ WITH [ NO ] DATA ]
CREATE TABLE AS
creates a table and fills it
with data computed by a SELECT
command.
The table columns have the
names and data types associated with the output columns of the
SELECT
(except that you can override the column
names by giving an explicit list of new column names).
CREATE TABLE AS
bears some resemblance to
creating a view, but it is really quite different: it creates a new
table and evaluates the query just once to fill the new table
initially. The new table will not track subsequent changes to the
source tables of the query. In contrast, a view re-evaluates its
defining SELECT
statement whenever it is
queried.
CREATE TABLE AS
requires CREATE
privilege on the schema used for the table.
GLOBAL
or LOCAL
Ignored for compatibility. Use of these keywords is deprecated; refer to CREATE TABLE for details.
TEMPORARY
or TEMP
If specified, the table is created as a temporary table. Refer to CREATE TABLE for details.
UNLOGGED
If specified, the table is created as an unlogged table. Refer to CREATE TABLE for details.
IF NOT EXISTS
Do not throw an error if a relation with the same name already exists; simply issue a notice and leave the table unmodified.
table_name
The name (optionally schema-qualified) of the table to be created.
column_name
The name of a column in the new table. If column names are not provided, they are taken from the output column names of the query.
USING method
This optional clause specifies the table access method to use to store
the contents for the new table; the method needs be an access method of
type TABLE
. See Chapter 61 for more
information. If this option is not specified, the default table access
method is chosen for the new table. See default_table_access_method for more information.
WITH ( storage_parameter
[= value
] [, ... ] )
This clause specifies optional storage parameters for the new table;
see Storage Parameters in the
CREATE TABLE documentation for more
information. For backward-compatibility the WITH
clause for a table can also include OIDS=FALSE
to
specify that rows of the new table should contain no OIDs (object
identifiers), OIDS=TRUE
is not supported anymore.
WITHOUT OIDS
This is backward-compatible syntax for declaring a table
WITHOUT OIDS
, creating a table WITH
OIDS
is not supported anymore.
ON COMMIT
The behavior of temporary tables at the end of a transaction
block can be controlled using ON COMMIT
.
The three options are:
PRESERVE ROWS
No special action is taken at the ends of transactions. This is the default behavior.
DELETE ROWS
All rows in the temporary table will be deleted at the end
of each transaction block. Essentially, an automatic TRUNCATE
is done
at each commit.
DROP
The temporary table will be dropped at the end of the current transaction block.
TABLESPACE tablespace_name
The tablespace_name
is the name
of the tablespace in which the new table is to be created.
If not specified,
default_tablespace is consulted, or
temp_tablespaces if the table is temporary.
query
A SELECT
, TABLE
, or VALUES
command, or an EXECUTE
command that runs a
prepared SELECT
, TABLE
, or
VALUES
query.
WITH [ NO ] DATA
This clause specifies whether or not the data produced by the query should be copied into the new table. If not, only the table structure is copied. The default is to copy the data.
This command is functionally similar to SELECT INTO, but it is
preferred since it is less likely to be confused with other uses of
the SELECT INTO
syntax. Furthermore, CREATE
TABLE AS
offers a superset of the functionality offered
by SELECT INTO
.
Create a new table films_recent
consisting of only
recent entries from the table films
:
CREATE TABLE films_recent AS SELECT * FROM films WHERE date_prod >= '2002-01-01';
To copy a table completely, the short form using
the TABLE
command can also be used:
CREATE TABLE films2 AS TABLE films;
Create a new temporary table films_recent
, consisting of
only recent entries from the table films
, using a
prepared statement. The new table will be dropped at commit:
PREPARE recentfilms(date) AS SELECT * FROM films WHERE date_prod > $1; CREATE TEMP TABLE films_recent ON COMMIT DROP AS EXECUTE recentfilms('2002-01-01');
CREATE TABLE AS
conforms to the SQL
standard. The following are nonstandard extensions:
The standard requires parentheses around the subquery clause; in PostgreSQL, these parentheses are optional.
In the standard, the WITH [ NO ] DATA
clause
is required; in PostgreSQL it is optional.
PostgreSQL handles temporary tables in a way rather different from the standard; see CREATE TABLE for details.
The WITH
clause is a PostgreSQL
extension; storage parameters are not in the standard.
The PostgreSQL concept of tablespaces is not
part of the standard. Hence, the clause TABLESPACE
is an extension.