create_view(7)

1CREATE VIEW(7)                   SQL Commands                   CREATE VIEW(7)
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NAME

6       CREATE VIEW - define a new view
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SYNOPSIS

10       CREATE [ OR REPLACE ] [ TEMP | TEMPORARY ] VIEW name [ ( column_name [, ...] ) ]
11           AS query
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DESCRIPTION

15       CREATE VIEW defines a view of a query. The view is not physically mate‐
16       rialized. Instead, the query is run every time the view  is  referenced
17       in a query.
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19       CREATE  OR  REPLACE  VIEW  is  similar,  but if a view of the same name
20       already exists, it is replaced. The new query must  generate  the  same
21       columns  that  were  generated by the existing view query (that is, the
22       same column names in the same order and with the same data types),  but
23       it  may add additional columns to the end of the list. The calculations
24       giving rise to the output columns may be completely different.
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26       If a schema name is given (for  example,  CREATE  VIEW  myschema.myview
27       ...)  then the view is created in the specified schema. Otherwise it is
28       created in the current schema.  Temporary  views  exist  in  a  special
29       schema,  so  a  schema  name  cannot be given when creating a temporary
30       view. The name of the view must be distinct from the name of any  other
31       view, table, sequence, or index in the same schema.
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PARAMETERS

34       TEMPORARY or TEMP
35              If  specified,  the view is created as a temporary view.  Tempo‐
36              rary views are automatically dropped at the end of  the  current
37              session. Existing permanent relations with the same name are not
38              visible to the current session while the temporary view  exists,
39              unless they are referenced with schema-qualified names.
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41              If  any  of the tables referenced by the view are temporary, the
42              view is created as a temporary view (whether TEMPORARY is speci‐
43              fied or not).
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45       name   The name (optionally schema-qualified) of a view to be created.
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47       column_name
48              An  optional  list  of names to be used for columns of the view.
49              If not given, the column names are deduced from the query.
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51       query  A SELECT [select(7)] or VALUES [values(7)]  command  which  will
52              provide the columns and rows of the view.
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NOTES

55       Currently,  views  are  read only: the system will not allow an insert,
56       update, or delete on a view. You can get the  effect  of  an  updatable
57       view  by  creating  rules  that  rewrite inserts, etc. on the view into
58       appropriate actions on other tables. For more  information  see  CREATE
59       RULE [create_rule(7)].
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61       Use the DROP VIEW [drop_view(7)] statement to drop views.
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63       Be  careful  that  the  names  and  types of the view's columns will be
64       assigned the way you want. For example:
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66       CREATE VIEW vista AS SELECT 'Hello World';
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68       is bad form in two ways: the column name defaults to ?column?, and  the
69       column data type defaults to unknown. If you want a string literal in a
70       view's result, use something like:
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72       CREATE VIEW vista AS SELECT text 'Hello World' AS hello;
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75       Access to tables referenced in the view is determined by permissions of
76       the  view  owner. In some cases, this can be used to provide secure but
77       restricted access to the underlying tables. However, not all views  are
78       secure  against  tampering; see in the documentation for details. Func‐
79       tions called in the view are treated the  same  as  if  they  had  been
80       called  directly from the query using the view. Therefore the user of a
81       view must have permissions to call all functions used by the view.
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83       When CREATE OR REPLACE VIEW is used  on  an  existing  view,  only  the
84       view's defining SELECT rule is changed.  Other view properties, includ‐
85       ing ownership, permissions, and non-SELECT rules, remain unchanged. You
86       must  own  the  view to replace it (this includes being a member of the
87       owning role).
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EXAMPLES

90       Create a view consisting of all comedy films:
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92       CREATE VIEW comedies AS
93           SELECT *
94           FROM films
95           WHERE kind = 'Comedy';
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COMPATIBILITY

99       The SQL standard specifies some additional capabilities for the  CREATE
100       VIEW statement:
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102       CREATE VIEW name [ ( column_name [, ...] ) ]
103           AS query
104           [ WITH [ CASCADED | LOCAL ] CHECK OPTION ]
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107       The optional clauses for the full SQL command are:
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109       CHECK OPTION
110              This  option  has  to  do  with  updatable views. All INSERT and
111              UPDATE commands on the view will be checked to ensure data  sat‐
112              isfy the view-defining condition (that is, the new data would be
113              visible through the view). If they do not, the  update  will  be
114              rejected.
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116       LOCAL  Check for integrity on this view.
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118       CASCADED
119              Check for integrity on this view and on any dependent view. CAS‐
120              CADED is assumed if neither CASCADED nor LOCAL is specified.
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122       CREATE OR REPLACE VIEW is a PostgreSQL language extension.  So  is  the
123       concept of a temporary view.
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