PostgreSQL中临时视图

Oracle中创建视图的语法，没有临时视图这概念

CREATE [OR REPLACE]
  [[NO] FORCE] [EDITIONING] VIEW [schema.] view
   [ ( { alias [ inline_constraint... ]
       | out_of_line_constraint
       }
         [, { alias [ inline_constraint...]
            | out_of_line_constraint
     }
  ]
     )
   | object_view_clause
   | XMLType_view_clause
   ]
   AS subquery [ subquery_restriction_clause ] ;

PostgreSQL中有临时视图，session结束时，视图就会消失
db03=# \h create view

Command:     CREATE VIEW

Description: define a new view

Syntax:

CREATE [ OR REPLACE ] [ TEMP | TEMPORARY ] [ RECURSIVE ] VIEW name [ ( column_name [, ...] ) ]
     [ WITH ( view_option_name [= view_option_value] [, ... ] ) ]
     AS query
     [ WITH [ CASCADED | LOCAL ] CHECK OPTION ]
测试：
db03=# select pg_backend_pid();
  pg_backend_pid 

----------------
            3043

(1 row)

db03=# create temp view temp_view as select * from pg_class;

CREATE VIEW

db03=# select count(*) from temp_view;
  count 

-------
    346

(1 row)

db03=# select current_database();
  current_database 

------------------
  db03

(1 row)

db03=# \c postgres

You are now connected to database "postgres" as user "postgres".

postgres=# \c db03

You are now connected to database "db03" as user "postgres".

db03=# select current_database();
  current_database 

------------------
  db03

(1 row)

db03=# select count(*) from temp_view;

ERROR:  relation "temp_view" does not exist

LINE 1: select count(*) from temp_view;
                              ^

db03=# select pg_backend_pid();
  pg_backend_pid 

----------------
            3066

(1 row)