NAME

CREATE TABLE AS - 從一條查詢的結果中創(chuàng)建一個新表

SYNOPSIS

CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } ] TABLE table_name [ (column_name [, ...] ) ]
    AS query

DESCRIPTION 描述

CREATE TABLE AS 創(chuàng)建一個表并且用來自 SELECT 命令計算出來的數(shù)據(jù)填充該表。 該表的字段和 SELECT 輸出字段的名字及類型相關。 （只不過你可以通過明確地給出一個字段名字列表來覆蓋 SELECT 的字段名）。

CREATE TABLE AS 和創(chuàng)建視圖有點象， 不過兩者之間實在是有比較大差異：它創(chuàng)建一個新表并且只對 SELECT 計算一次來填充這個新表。 新表不能跟蹤 SELECT 的源表隨后做的變化。 相比之下，每次做查詢的時候，視圖都重新計算定義它的 SELECT 語句。  

PARAMETERS 參數(shù)

TEMPORARY or TEMP

 如果聲明了這個選項，則該表作為臨時表創(chuàng)建。 參閱 CREATE TABLE [create_table(7)] 獲取細節(jié)。

table_name

 要創(chuàng)建的表名（可以是用模式修飾的）。

column_name

 字段的名稱。如果沒有提供字段名字，那么就從查詢的輸出字段名中獲取。 如果表是一個 EXECUTE 命令創(chuàng)建的， 那么當前就不能聲明字段名列表。

query

 一個查詢語句（也就是一條 SELECT 命令或者一條運行準備好的 SELECT 命令的 EXECUTE 命令），請分別參考 SELECT [select(7)] 或者 EXECUTE [execute(l)] 獲取可以使用的語法的描述。

NOTES 注意

 這條命令從功能上等效于 SELECT INTO [select_into(7)]， 但是我們更建議你用這個命令，因為它不太可能和 SELECT ... INTO 語法的其它方面的使用混淆。  

COMPATIBILITY 兼容性

 這條命令是根據(jù) Oracle 的一個特性制作的。 在 SQL 標準中沒有功能相等的命令。不過， 把 CREATE TABLE 和 INSERT ... SELECT  組合起來可以通過略微多一些的工作完成同樣的事情。  

SEE ALSO 參見

CREATE TABLE [create_table(7)], CREATE VIEW [create_view(l)], EXECUTE [execute(l)], SELECT [select(l)], SELECT INTO [select_into(l)]  

#p#

NAME

CREATE TABLE AS - create a new table from the results of a query

SYNOPSIS

CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } ] TABLE table_name [ (column_name [, ...] ) ]
    AS query

DESCRIPTION

CREATE TABLE AS creates a table and fills it with data computed by a SELECT command or an EXECUTE that runs a prepared 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

TEMPORARY or TEMP

If specified, the table is created as a temporary table. 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. If the table is created out of an EXECUTE command, a column name list can currently not be specified.

query

A query statement (that is, a SELECT command or an EXECUTE command that runs a prepared SELECT command). Refer to SELECT [select(7)] or EXECUTE [execute(l)], respectively, for a description of the allowed syntax.

NOTES

This command is functionally equivalent 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.  

COMPATIBILITY

This command is modeled after an Oracle feature. There is no command with equivalent functionality in the SQL standard. However, a combination of CREATE TABLE and INSERT ... SELECT can accomplish the same thing with little more effort.  

SEE ALSO

CREATE TABLE [create_table(7)], CREATE VIEW [create_view(l)], EXECUTE [execute(l)], SELECT [select(l)], SELECT INTO [select_into(l)]