Postgresql 中文操作指南

CREATE TABLE AS

CREATE TABLE AS — 根据查询结果定义一个新表

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 创建一个表，并用 SELECT 命令计算的数据填充该表。表列具有与 SELECT 的输出列关联的名称和数据类型（但您可以通过给出一个新的显式列名列表来覆盖列名）。

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 与创建视图有一些相似之处，但实际上有很大不同：它创建了一个新表，并仅计算一次查询以最初填充新表。新表不会跟踪源表的后续更改。相比之下，视图只要查询就会重新计算其定义的 SELECT 语句。

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 要求对用于表的架构有 CREATE 权限。

CREATE TABLE AS requires CREATE privilege on the schema used for the table.

Parameters

  • 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 63 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:

  • 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

  • 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.

  • 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.

Notes

此命令在功能上与 SELECT INTO 类似，但由于不太可能与 SELECT INTO 语法的其他用法混淆，因此更受青睐。此外， CREATE TABLE AS 提供了 SELECT INTO 所提供功能的超集。

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

创建新表 films_recent ，其中仅包含表 films 中的近期条目：

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';

若要完全复制表，还可以使用 TABLE 命令的简短形式：

To copy a table completely, the short form using the TABLE command can also be used:

CREATE TABLE films2 AS
  TABLE films;

使用已准备好的语句，创建新临时表 films_recent ，其中仅包含表 films 中的近期条目。新表将在提交时删除：

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 符合 SQL 标准。以下是非标准扩展：

CREATE TABLE AS conforms to the SQL standard. The following are nonstandard extensions:

See Also

CREATE MATERIALIZED VIEW 、 CREATE TABLE 、 EXECUTE 、 SELECT 、 SELECT INTO 、 VALUES

CREATE MATERIALIZED VIEW, CREATE TABLE, EXECUTE, SELECT, SELECT INTO, VALUES