NAME¶
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 [, ...] ) ]
[ USING method ]
[ WITH ( storage_parameter [= value] [, ... ] ) | WITHOUT OIDS ]
[ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
[ TABLESPACE tablespace_name ]
AS query
[ 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 or LOCAL
Ignored for compatibility. Use of these keywords is
deprecated; refer to CREATE TABLE (CREATE_TABLE(7)) for details.
TEMPORARY or TEMP
If specified, the table is created as a temporary table.
Refer to CREATE TABLE (CREATE_TABLE(7)) for details.
UNLOGGED
If specified, the table is created as an unlogged table.
Refer to CREATE TABLE (CREATE_TABLE(7)) for details.
IF NOT EXISTS
Do not throw an error if a relation with the same name
already exists. A notice is issued in this case. Refer to CREATE TABLE
(CREATE_TABLE(7)) for details.
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 60 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 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(7) 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(7), TABLE, or VALUES(7) command,
or an EXECUTE(7) 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.
NOTES¶
This command is functionally similar to SELECT INTO
(SELECT_INTO(7)), 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 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 (CREATE_TABLE(7))
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.
SEE ALSO¶
CREATE MATERIALIZED VIEW (CREATE_MATERIALIZED_VIEW(7)),
CREATE TABLE (CREATE_TABLE(7)), EXECUTE(7), SELECT(7),
SELECT INTO (SELECT_INTO(7)), VALUES(7)
