75 lines
4.3 KiB
HTML
75 lines
4.3 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 2005" />
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<meta name="DC.rights.owner" content="(C) Copyright IBM Corporation 2005" />
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<meta name="DC.Type" content="task" />
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<meta name="DC.Title" content="Create and use a view" />
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<meta name="DC.Relation" scheme="URI" content="rzatcgetstartsql.htm" />
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<meta name="DC.Relation" scheme="URI" content="rzatccrtviewsql.htm" />
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<meta name="DC.Relation" scheme="URI" content="rzatcviewmultsql.htm" />
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<meta name="DC.Identifier" content="viewsql" />
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<meta name="DC.Language" content="en-us" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Create and use a view</title>
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</head>
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<body id="viewsql"><a name="viewsql"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Create and use a view</h1>
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<div><div class="section">You might find that no single table contains all the information
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you need. You might also want to give users access to only part of the data
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in a table. Views provide a way to subset the table so that you deal with
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only the data you need. A view reduces complexity and, at the same time, restricts
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access.<p>You can create a view using the SQL CREATE VIEW statement. Using
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the CREATE VIEW statement, defining a view on a table is like creating a new
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table containing just the columns and rows you want. When your application
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uses a view, it cannot access rows or columns of the table that are not included
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in the view. However, rows that do not match the selection criteria can still
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be inserted through a view if the SQL WITH CHECK OPTION is not used. See <a href="../sqlp/rbafywcohdg.htm">WITH CHECK OPTION on a View</a> in
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the SQL Programming topic for more information about using WITH CHECK OPTION.</p>
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<p>In
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order to create a view you must have the proper authority to the tables or
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physical files on which the view is based. See the <a href="../db2/rbafzmsthcview.htm">CREATE
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VIEW statement</a> in the SQL Reference topic for a list of authorities
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needed.</p>
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<p>If you did not specify column names in the view definition,
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the column names are the same as those for the table on which
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the view is based.</p>
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<p>You can make changes to a table through a view even
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if the view has a different number of columns or rows than the table. For
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INSERT, columns in the table that are not in the view must have a default
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value.</p>
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<p>You can use the view as though it were a table, even though the
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view is totally dependent on one or more tables for data. The view has no
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data of its own and therefore requires no storage for the data. Because a
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view is derived from a table that exists in storage, when you update the view
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data, you are really updating data in the table. Therefore, views are automatically
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kept up-to-date as the tables they depend on are updated.</p>
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</div>
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</div>
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<div>
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<ul class="ullinks">
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<li class="ulchildlink"><strong><a href="rzatccrtviewsql.htm">Create a view on a single table</a></strong><br />
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</li>
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<li class="ulchildlink"><strong><a href="rzatcviewmultsql.htm">Create a view combining data from multiple tables</a></strong><br />
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</li>
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</ul>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzatcgetstartsql.htm" title="This topic describes how to create and work with schemas, tables, and views using SQL statements in interactive SQL.">Get started with SQL</a></div>
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</div>
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</div>
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</body>
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</html>
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