<REFENTRY ID="SQL-CREATEVIEW">
 <REFMETA>
  <REFENTRYTITLE>
   CREATE VIEW
  </REFENTRYTITLE>
  <REFMISCINFO>SQL - Language Statements</REFMISCINFO>
 </REFMETA>
 <REFNAMEDIV>
  <REFNAME>
   CREATE VIEW
  </REFNAME>
  <REFPURPOSE>
Constructs a virtual table
  </REFPURPOSE>
 <REFSYNOPSISDIV>
  <REFSYNOPSISDIVINFO>
   <DATE>1998-09-21</DATE>
  </REFSYNOPSISDIVINFO>
  <SYNOPSIS>
CREATE VIEW <REPLACEABLE CLASS="PARAMETER">view</REPLACEABLE>
    AS SELECT <REPLACEABLE CLASS="PARAMETER">query</REPLACEABLE>
  </SYNOPSIS>
  
  <REFSECT2 ID="R2-SQL-CREATEVIEW-1">
   <REFSECT2INFO>
    <DATE>1998-09-21</DATE>
   </REFSECT2INFO>
   <TITLE>
    Inputs
   </TITLE>
   <PARA>
       <VARIABLELIST>
	<VARLISTENTRY>
	 <TERM>
	  <ReturnValue><replaceable class="parameter">view</replaceable></ReturnValue>
	 </TERM>
	 <LISTITEM>
	  <PARA>
          The name of a view to be created.
	  </PARA>
	 </LISTITEM>
	</VARLISTENTRY>
	<VARLISTENTRY>
	 <TERM>
	  <ReturnValue><replaceable class="parameter">query</replaceable></ReturnValue>
	 </TERM>
	 <LISTITEM>
	  <PARA>
An SQL query which will provide the columns and rows of the view.
	  </PARA>
	  <PARA>
	   Refer to the SELECT statement for more information
	   about valid arguments.
	  </PARA>
	 </LISTITEM>
	</VARLISTENTRY>
       </variablelist>
  </REFSECT2>
  
  <REFSECT2 ID="R2-SQL-CREATEVIEW-2">
   <REFSECT2INFO>
    <DATE>1998-09-21</DATE>
   </REFSECT2INFO>
   <TITLE>
    Outputs
   </TITLE>
   <PARA>
       <VARIABLELIST>
	<VARLISTENTRY>
	 <TERM>
	  <ReturnValue>CREATE</ReturnValue>
	 </TERM>
	 <LISTITEM>
	  <PARA>
          The message returned if the view is successfully created.
	  </PARA>
	 </LISTITEM>
	</VARLISTENTRY>
	<VARLISTENTRY>
	 <TERM>
	  <ReturnValue>
	   WARN amcreate: "<replaceable class="parameter">view</replaceable>" relation already exists
	  </ReturnValue>
	 </TERM>
	 <LISTITEM>
	  <PARA>
          This error occurs if the view specified already exists in the database.
	  </PARA>
	 </LISTITEM>
	</VARLISTENTRY>
	<VARLISTENTRY>
	 <TERM>
	  <ReturnValue>NOTICE create: attribute named "<replaceable class="parameter">column</replaceable>" has an unknown type</ReturnValue>
	 </TERM>
	 <LISTITEM>
	  <PARA>
          The view will be created having a column with an unknown type
	   if you do not specify it. For example, the following command gives
	   an error:
	   <programlisting>
	    CREATE VIEW vista AS SELECT 'Hello World'
	   </programlisting>
	   whereas this command does not:
	   <programlisting>
	    CREATE VIEW vista AS SELECT 'Hello World'::text
	   </programlisting>

   </VARIABLELIST>
  </REFSECT2>
 </REFSYNOPSISDIV>
 
 <REFSECT1 ID="R1-SQL-CREATEVIEW-1">
  <REFSECT1INFO>
   <DATE>1998-09-21</DATE>
  </REFSECT1INFO>
  <TITLE>
   Description
  </TITLE>
  <PARA>
   CREATE VIEW will define a view of a table. This view is
   not physically materialized. Specifically, a query
   rewrite retrieve rule is automatically generated
   to support retrieve operations on views.
  </PARA>
  
  <REFSECT2 ID="R2-SQL-CREATEVIEW-3">
   <REFSECT2INFO>
    <DATE>1998-09-21</DATE>
   </REFSECT2INFO>
   <TITLE>
    Notes
   </TITLE>
   <PARA>
   Use the DROP VIEW statement to drop views.
   </PARA>
  </refsect2>
  
  <REFSECT2 ID="R2-SQL-CREATEVIEW-4">
   <REFSECT2INFO>
    <DATE>1998-09-21</DATE>
   </REFSECT2INFO>
   <TITLE>
    Bugs
   </TITLE>
   <para>
   Currently, views are read only.
   </para>
  </REFSECT2>
  
 <REFSECT1 ID="R1-SQL-CREATEVIEW-2">
  <TITLE>
   Usage
  </TITLE>
  <PARA>
   Create a view consisting of all Comedy films:
  </PARA>
  <ProgramListing>
CREATE VIEW kinds AS
    SELECT *
    FROM films
    WHERE kind = 'Comedy';

SELECT * FROM kinds;

code |title                    |did| date_prod|kind      |len
-----+-------------------------+---+----------+----------+------
UA502|Bananas                  |105|1971-07-13|Comedy    | 01:22
C_701|There's a Girl in my Soup|107|1970-06-11|Comedy    | 01:36
  </ProgramListing>
  
 </REFSECT1>
 
 <REFSECT1 ID="R1-SQL-CREATEVIEW-3">
  <TITLE>
   Compatibility
  </TITLE>
  <PARA>
  </PARA>
  
  <REFSECT2 ID="R2-SQL-CREATEVIEW-5">
   <REFSECT2INFO>
    <DATE>1998-09-21</DATE>
   </REFSECT2INFO>
   <TITLE>
    SQL92
   </TITLE>
   <PARA>
   SQL92 specifies some additional capabilities for the CREATE VIEW statement:
   </PARA>
   <synopsis>
CREATE VIEW <replaceable class="parameter">view</replaceable> [ <replaceable class="parameter">column</replaceable> [, ...] ]
    AS SELECT <replaceable class="parameter">expression</replaceable> [AS <replaceable class="parameter">colname</replaceable>] [, ...]
    FROM <replaceable class="parameter">table</replaceable>
    [ WHERE <replaceable class="parameter">condition</replaceable> ]
    [ WITH [ CASCADE | LOCAL ] CHECK OPTION ]
   </synopsis>

   <VARIABLELIST>
    <VARLISTENTRY>
     <TERM>
     </TERM>
     <LISTITEM>
      <PARA>
       <VARIABLELIST>
	<VARLISTENTRY>
	 <TERM>
	  CHECK OPTION
	 </TERM>
	 <LISTITEM>
	  <PARA> This option is to do with updatable views.
                     All INSERTs and UPDATEs on the view will be
                     checked to ensure data satisfy the view-defining
                     condition. If they do not, the update will be rejected.
	  </PARA>
	 </LISTITEM>
	</VARLISTENTRY>
	<VARLISTENTRY>
	 <TERM>
	  LOCAL
	 </TERM>
	 <LISTITEM>
	  <PARA>
	   Check for integrity on this view.
	  </PARA>
	 </LISTITEM>
	</VARLISTENTRY>
	<VARLISTENTRY>
	 <TERM>
	  CASCADE
	 </TERM>
	 <LISTITEM>
	  <PARA>
	   Check for integrity on this view and on any dependent
	   view. CASCADE is assumed if neither CASCADE nor LOCAL is specified.
	  </PARA>
	 </LISTITEM>
	</VARLISTENTRY>
       </variablelist>
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </refsect2>
 </refsect1>
</REFENTRY>


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