CREATE TABLE AS
CREATE TABLE AS — define a new table from the results of a query
Synopsis
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 ]
Description
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.
Parameters
GLOBAL
orLOCAL
Ignored for compatibility. Use of these keywords is deprecated; refer to CREATE TABLE for details.
TEMPORARY
orTEMP
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 56 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 for more information. For backward-compatibility the
WITH
clause for a table can also includeOIDS=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 tableWITH 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
, orVALUES
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.
Notes
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
.
Examples
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');
Compatibility
CREATE TABLE AS
conforms to the SQL standard. The following are nonstandard extensions:
The standard requires parentheses around the subquery clause; in Postgres Pro, these parentheses are optional.
In the standard, the
WITH [ NO ] DATA
clause is required; in Postgres Pro it is optional.Postgres Pro handles temporary tables in a way rather different from the standard; see CREATE TABLE for details.
The
WITH
clause is a Postgres Pro extension; storage parameters are not in the standard.The Postgres Pro concept of tablespaces is not part of the standard. Hence, the clause
TABLESPACE
is an extension.