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1<?xml version="1.0" encoding="UTF-8" standalone="no"?>2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>CREATE VIEW</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="sql-createusermapping.html" title="CREATE USER MAPPING" /><link rel="next" href="sql-deallocate.html" title="DEALLOCATE" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">CREATE VIEW</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="sql-createusermapping.html" title="CREATE USER MAPPING">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="sql-commands.html" title="SQL Commands">Up</a></td><th width="60%" align="center">SQL Commands</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="sql-deallocate.html" title="DEALLOCATE">Next</a></td></tr></table><hr /></div><div class="refentry" id="SQL-CREATEVIEW"><div class="titlepage"></div><a id="id-1.9.3.97.1" class="indexterm"></a><div class="refnamediv"><h2><span class="refentrytitle">CREATE VIEW</span></h2><p>CREATE VIEW — define a new view</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis">3CREATE [ OR REPLACE ] [ TEMP | TEMPORARY ] [ RECURSIVE ] VIEW <em class="replaceable"><code>name</code></em> [ ( <em class="replaceable"><code>column_name</code></em> [, ...] ) ]4    [ WITH ( <em class="replaceable"><code>view_option_name</code></em> [= <em class="replaceable"><code>view_option_value</code></em>] [, ... ] ) ]5    AS <em class="replaceable"><code>query</code></em>6    [ WITH [ CASCADED | LOCAL ] CHECK OPTION ]7</pre></div><div class="refsect1" id="id-1.9.3.97.5"><h2>Description</h2><p>8   <code class="command">CREATE VIEW</code> defines a view of a query.  The view9   is not physically materialized. Instead, the query is run every time10   the view is referenced in a query.11  </p><p>12   <code class="command">CREATE OR REPLACE VIEW</code> is similar, but if a view13   of the same name already exists, it is replaced.  The new query must14   generate the same columns that were generated by the existing view query15   (that is, the same column names in the same order and with the same data16   types), but it may add additional columns to the end of the list.  The17   calculations giving rise to the output columns may be completely different.18  </p><p>19   If a schema name is given (for example, <code class="literal">CREATE VIEW20   myschema.myview ...</code>) then the view is created in the specified21   schema.  Otherwise it is created in the current schema.  Temporary22   views exist in a special schema, so a schema name cannot be given23   when creating a temporary view. The name of the view must be24   distinct from the name of any other relation (table, sequence, index, view,25   materialized view, or foreign table) in the same schema.26  </p></div><div class="refsect1" id="id-1.9.3.97.6"><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">TEMPORARY</code> or <code class="literal">TEMP</code></span></dt><dd><p>27      If specified, the view is created as a temporary view.28      Temporary views are automatically dropped at the end of the29      current session.  Existing30      permanent relations with the same name are not visible to the31      current session while the temporary view exists, unless they are32      referenced with schema-qualified names.33     </p><p>34      If any of the tables referenced by the view are temporary,35      the view is created as a temporary view (whether36      <code class="literal">TEMPORARY</code> is specified or not).37     </p></dd><dt><span class="term"><code class="literal">RECURSIVE</code>38      <a id="id-1.9.3.97.6.2.2.1.2" class="indexterm"></a>39    </span></dt><dd><p>40      Creates a recursive view.  The syntax41</p><pre class="synopsis">42CREATE RECURSIVE VIEW [ <em class="replaceable"><code>schema</code></em> . ] <em class="replaceable"><code>view_name</code></em> (<em class="replaceable"><code>column_names</code></em>) AS SELECT <em class="replaceable"><code>...</code></em>;43</pre><p>44      is equivalent to45</p><pre class="synopsis">46CREATE VIEW [ <em class="replaceable"><code>schema</code></em> . ] <em class="replaceable"><code>view_name</code></em> AS WITH RECURSIVE <em class="replaceable"><code>view_name</code></em> (<em class="replaceable"><code>column_names</code></em>) AS (SELECT <em class="replaceable"><code>...</code></em>) SELECT <em class="replaceable"><code>column_names</code></em> FROM <em class="replaceable"><code>view_name</code></em>;47</pre><p>48      A view column name list must be specified for a recursive view.49     </p></dd><dt><span class="term"><em class="replaceable"><code>name</code></em></span></dt><dd><p>50      The name (optionally schema-qualified) of a view to be created.51     </p></dd><dt><span class="term"><em class="replaceable"><code>column_name</code></em></span></dt><dd><p>52      An optional list of names to be used for columns of the view.53      If not given, the column names are deduced from the query.54     </p></dd><dt><span class="term"><code class="literal">WITH ( <em class="replaceable"><code>view_option_name</code></em> [= <em class="replaceable"><code>view_option_value</code></em>] [, ... ] )</code></span></dt><dd><p>55      This clause specifies optional parameters for a view; the following56      parameters are supported:57 58      </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">check_option</code> (<code class="type">enum</code>)</span></dt><dd><p>59          This parameter may be either <code class="literal">local</code> or60          <code class="literal">cascaded</code>, and is equivalent to specifying61          <code class="literal">WITH [ CASCADED | LOCAL ] CHECK OPTION</code> (see below).62         </p></dd><dt><span class="term"><code class="literal">security_barrier</code> (<code class="type">boolean</code>)</span></dt><dd><p>63          This should be used if the view is intended to provide row-level64          security.  See <a class="xref" href="rules-privileges.html" title="41.5. Rules and Privileges">Section 41.5</a> for full details.65         </p></dd><dt><span class="term"><code class="literal">security_invoker</code> (<code class="type">boolean</code>)</span></dt><dd><p>66          This option causes the underlying base relations to be checked67          against the privileges of the user of the view rather than the view68          owner.  See the notes below for full details.69         </p></dd></dl></div><p>70 71      All of the above options can be changed on existing views using <a class="link" href="sql-alterview.html" title="ALTER VIEW"><code class="command">ALTER VIEW</code></a>.72     </p></dd><dt><span class="term"><em class="replaceable"><code>query</code></em></span></dt><dd><p>73      A <a class="link" href="sql-select.html" title="SELECT"><code class="command">SELECT</code></a> or74      <a class="link" href="sql-values.html" title="VALUES"><code class="command">VALUES</code></a> command75      which will provide the columns and rows of the view.76     </p></dd><dt><span class="term"><code class="literal">WITH [ CASCADED | LOCAL ] CHECK OPTION</code>77      <a id="id-1.9.3.97.6.2.7.1.2" class="indexterm"></a>78      <a id="id-1.9.3.97.6.2.7.1.3" class="indexterm"></a>79    </span></dt><dd><p>80      This option controls the behavior of automatically updatable views.  When81      this option is specified, <code class="command">INSERT</code> and <code class="command">UPDATE</code>82      commands on the view will be checked to ensure that new rows satisfy the83      view-defining condition (that is, the new rows are checked to ensure that84      they are visible through the view).  If they are not, the update will be85      rejected.  If the <code class="literal">CHECK OPTION</code> is not specified,86      <code class="command">INSERT</code> and <code class="command">UPDATE</code> commands on the view are87      allowed to create rows that are not visible through the view.  The88      following check options are supported:89 90      </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">LOCAL</code></span></dt><dd><p>91          New rows are only checked against the conditions defined directly in92          the view itself.  Any conditions defined on underlying base views are93          not checked (unless they also specify the <code class="literal">CHECK OPTION</code>).94         </p></dd><dt><span class="term"><code class="literal">CASCADED</code></span></dt><dd><p>95          New rows are checked against the conditions of the view and all96          underlying base views.  If the <code class="literal">CHECK OPTION</code> is specified,97          and neither <code class="literal">LOCAL</code> nor <code class="literal">CASCADED</code> is specified,98          then <code class="literal">CASCADED</code> is assumed.99         </p></dd></dl></div><p>100     </p><p>101      The <code class="literal">CHECK OPTION</code> may not be used with <code class="literal">RECURSIVE</code>102      views.103     </p><p>104      Note that the <code class="literal">CHECK OPTION</code> is only supported on views that105      are automatically updatable, and do not have <code class="literal">INSTEAD OF</code>106      triggers or <code class="literal">INSTEAD</code> rules.  If an automatically updatable107      view is defined on top of a base view that has <code class="literal">INSTEAD OF</code>108      triggers, then the <code class="literal">LOCAL CHECK OPTION</code> may be used to check109      the conditions on the automatically updatable view, but the conditions110      on the base view with <code class="literal">INSTEAD OF</code> triggers will not be111      checked (a cascaded check option will not cascade down to a112      trigger-updatable view, and any check options defined directly on a113      trigger-updatable view will be ignored).  If the view or any of its base114      relations has an <code class="literal">INSTEAD</code> rule that causes the115      <code class="command">INSERT</code> or <code class="command">UPDATE</code> command to be rewritten, then116      all check options will be ignored in the rewritten query, including any117      checks from automatically updatable views defined on top of the relation118      with the <code class="literal">INSTEAD</code> rule.119     </p></dd></dl></div></div><div class="refsect1" id="id-1.9.3.97.7"><h2>Notes</h2><p>120    Use the <a class="link" href="sql-dropview.html" title="DROP VIEW"><code class="command">DROP VIEW</code></a>121    statement to drop views.122   </p><p>123    Be careful that the names and types of the view's columns will be124    assigned the way you want.  For example:125</p><pre class="programlisting">126CREATE VIEW vista AS SELECT 'Hello World';127</pre><p>128    is bad form because the column name defaults to <code class="literal">?column?</code>;129    also, the column data type defaults to <code class="type">text</code>, which might not130    be what you wanted.  Better style for a string literal in a view's131    result is something like:132</p><pre class="programlisting">133CREATE VIEW vista AS SELECT text 'Hello World' AS hello;134</pre><p>135   </p><p>136    By default, access to the underlying base relations referenced in the view137    is determined by the permissions of the view owner.  In some cases, this138    can be used to provide secure but restricted access to the underlying139    tables.  However, not all views are secure against tampering; see <a class="xref" href="rules-privileges.html" title="41.5. Rules and Privileges">Section 41.5</a> for details.140   </p><p>141    If the view has the <code class="literal">security_invoker</code> property set to142    <code class="literal">true</code>, access to the underlying base relations is143    determined by the permissions of the user executing the query, rather than144    the view owner.  Thus, the user of a security invoker view must have the145    relevant permissions on the view and its underlying base relations.146   </p><p>147    If any of the underlying base relations is a security invoker view, it148    will be treated as if it had been accessed directly from the original149    query.  Thus, a security invoker view will always check its underlying150    base relations using the permissions of the current user, even if it is151    accessed from a view without the <code class="literal">security_invoker</code>152    property.153   </p><p>154    If any of the underlying base relations has155    <a class="link" href="ddl-rowsecurity.html" title="5.8. Row Security Policies">row-level security</a> enabled, then156    by default, the row-level security policies of the view owner are applied,157    and access to any additional relations referred to by those policies is158    determined by the permissions of the view owner.  However, if the view has159    <code class="literal">security_invoker</code> set to <code class="literal">true</code>, then160    the policies and permissions of the invoking user are used instead, as if161    the base relations had been referenced directly from the query using the162    view.163   </p><p>164    Functions called in the view are treated the same as if they had been165    called directly from the query using the view.  Therefore, the user of166    a view must have permissions to call all functions used by the view.167    Functions in the view are executed with the privileges of the user168    executing the query or the function owner, depending on whether the169    functions are defined as <code class="literal">SECURITY INVOKER</code> or170    <code class="literal">SECURITY DEFINER</code>.  Thus, for example, calling171    <code class="literal">CURRENT_USER</code> directly in a view will always return the172    invoking user, not the view owner.  This is not affected by the view's173    <code class="literal">security_invoker</code> setting, and so a view with174    <code class="literal">security_invoker</code> set to <code class="literal">false</code> is175    <span class="emphasis"><em>not</em></span> equivalent to a176    <code class="literal">SECURITY DEFINER</code> function and those concepts should not177    be confused.178   </p><p>179    The user creating or replacing a view must have <code class="literal">USAGE</code>180    privileges on any schemas referred to in the view query, in order to look181    up the referenced objects in those schemas.  Note, however, that this182    lookup only happens when the view is created or replaced.  Therefore, the183    user of the view only requires the <code class="literal">USAGE</code> privilege on184    the schema containing the view, not on the schemas referred to in the view185    query, even for a security invoker view.186   </p><p>187    When <code class="command">CREATE OR REPLACE VIEW</code> is used on an existing188    view, only the view's defining SELECT rule, plus any189    <code class="literal">WITH ( ... )</code> parameters and its190    <code class="literal">CHECK OPTION</code> are changed.191    Other view properties, including ownership, permissions, and non-SELECT192    rules, remain unchanged.  You must own the view193    to replace it (this includes being a member of the owning role).194   </p><div class="refsect2" id="SQL-CREATEVIEW-UPDATABLE-VIEWS"><h3>Updatable Views</h3><a id="id-1.9.3.97.7.11.2" class="indexterm"></a><p>195    Simple views are automatically updatable: the system will allow196    <code class="command">INSERT</code>, <code class="command">UPDATE</code> and <code class="command">DELETE</code> statements197    to be used on the view in the same way as on a regular table.  A view is198    automatically updatable if it satisfies all of the following conditions:199 200    </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>201       The view must have exactly one entry in its <code class="literal">FROM</code> list,202       which must be a table or another updatable view.203      </p></li><li class="listitem"><p>204       The view definition must not contain <code class="literal">WITH</code>,205       <code class="literal">DISTINCT</code>, <code class="literal">GROUP BY</code>, <code class="literal">HAVING</code>,206       <code class="literal">LIMIT</code>, or <code class="literal">OFFSET</code> clauses at the top level.207      </p></li><li class="listitem"><p>208       The view definition must not contain set operations (<code class="literal">UNION</code>,209       <code class="literal">INTERSECT</code> or <code class="literal">EXCEPT</code>) at the top level.210      </p></li><li class="listitem"><p>211       The view's select list must not contain any aggregates, window functions212       or set-returning functions.213      </p></li></ul></div><p>214   </p><p>215    An automatically updatable view may contain a mix of updatable and216    non-updatable columns.  A column is updatable if it is a simple reference217    to an updatable column of the underlying base relation; otherwise the218    column is read-only, and an error will be raised if an <code class="command">INSERT</code>219    or <code class="command">UPDATE</code> statement attempts to assign a value to it.220   </p><p>221    If the view is automatically updatable the system will convert any222    <code class="command">INSERT</code>, <code class="command">UPDATE</code> or <code class="command">DELETE</code> statement223    on the view into the corresponding statement on the underlying base224    relation.  <code class="command">INSERT</code> statements that have an <code class="literal">ON225    CONFLICT UPDATE</code> clause are fully supported.226   </p><p>227    If an automatically updatable view contains a <code class="literal">WHERE</code>228    condition, the condition restricts which rows of the base relation are229    available to be modified by <code class="command">UPDATE</code> and <code class="command">DELETE</code>230    statements on the view.  However, an <code class="command">UPDATE</code> is allowed to231    change a row so that it no longer satisfies the <code class="literal">WHERE</code>232    condition, and thus is no longer visible through the view.  Similarly,233    an <code class="command">INSERT</code> command can potentially insert base-relation rows234    that do not satisfy the <code class="literal">WHERE</code> condition and thus are not235    visible through the view (<code class="literal">ON CONFLICT UPDATE</code> may236    similarly affect an existing row not visible through the view).237    The <code class="literal">CHECK OPTION</code> may be used to prevent238    <code class="command">INSERT</code> and <code class="command">UPDATE</code> commands from creating239    such rows that are not visible through the view.240   </p><p>241    If an automatically updatable view is marked with the242    <code class="literal">security_barrier</code> property then all the view's <code class="literal">WHERE</code>243    conditions (and any conditions using operators which are marked as <code class="literal">LEAKPROOF</code>)244    will always be evaluated before any conditions that a user of the view has245    added.   See <a class="xref" href="rules-privileges.html" title="41.5. Rules and Privileges">Section 41.5</a> for full details.  Note that,246    due to this, rows which are not ultimately returned (because they do not247    pass the user's <code class="literal">WHERE</code> conditions) may still end up being locked.248    <code class="command">EXPLAIN</code> can be used to see which conditions are249    applied at the relation level (and therefore do not lock rows) and which are250    not.251   </p><p>252    A more complex view that does not satisfy all these conditions is253    read-only by default: the system will not allow an insert, update, or254    delete on the view.  You can get the effect of an updatable view by255    creating <code class="literal">INSTEAD OF</code> triggers on the view, which must256    convert attempted inserts, etc. on the view into appropriate actions257    on other tables.  For more information see <a class="xref" href="sql-createtrigger.html" title="CREATE TRIGGER"><span class="refentrytitle">CREATE TRIGGER</span></a>.  Another possibility is to create rules258    (see <a class="xref" href="sql-createrule.html" title="CREATE RULE"><span class="refentrytitle">CREATE RULE</span></a>), but in practice triggers are259    easier to understand and use correctly.260   </p><p>261    Note that the user performing the insert, update or delete on the view262    must have the corresponding insert, update or delete privilege on the263    view.  In addition, by default, the view's owner must have the relevant264    privileges on the underlying base relations, whereas the user performing265    the update does not need any permissions on the underlying base relations266    (see <a class="xref" href="rules-privileges.html" title="41.5. Rules and Privileges">Section 41.5</a>).  However, if the view has267    <code class="literal">security_invoker</code> set to <code class="literal">true</code>, the268    user performing the update, rather than the view owner, must have the269    relevant privileges on the underlying base relations.270   </p></div></div><div class="refsect1" id="id-1.9.3.97.8"><h2>Examples</h2><p>271   Create a view consisting of all comedy films:272 273</p><pre class="programlisting">274CREATE VIEW comedies AS275    SELECT *276    FROM films277    WHERE kind = 'Comedy';278</pre><p>279   This will create a view containing the columns that are in the280   <code class="literal">film</code> table at the time of view creation.  Though281   <code class="literal">*</code> was used to create the view, columns added later to282   the table will not be part of the view.283  </p><p>284   Create a view with <code class="literal">LOCAL CHECK OPTION</code>:285 286</p><pre class="programlisting">287CREATE VIEW universal_comedies AS288    SELECT *289    FROM comedies290    WHERE classification = 'U'291    WITH LOCAL CHECK OPTION;292</pre><p>293   This will create a view based on the <code class="literal">comedies</code> view, showing294   only films with <code class="literal">kind = 'Comedy'</code> and295   <code class="literal">classification = 'U'</code>. Any attempt to <code class="command">INSERT</code> or296   <code class="command">UPDATE</code> a row in the view will be rejected if the new row297   doesn't have <code class="literal">classification = 'U'</code>, but the film298   <code class="literal">kind</code> will not be checked.299  </p><p>300   Create a view with <code class="literal">CASCADED CHECK OPTION</code>:301 302</p><pre class="programlisting">303CREATE VIEW pg_comedies AS304    SELECT *305    FROM comedies306    WHERE classification = 'PG'307    WITH CASCADED CHECK OPTION;308</pre><p>309   This will create a view that checks both the <code class="literal">kind</code> and310   <code class="literal">classification</code> of new rows.311  </p><p>312   Create a view with a mix of updatable and non-updatable columns:313 314</p><pre class="programlisting">315CREATE VIEW comedies AS316    SELECT f.*,317           country_code_to_name(f.country_code) AS country,318           (SELECT avg(r.rating)319            FROM user_ratings r320            WHERE r.film_id = f.id) AS avg_rating321    FROM films f322    WHERE f.kind = 'Comedy';323</pre><p>324   This view will support <code class="command">INSERT</code>, <code class="command">UPDATE</code> and325   <code class="command">DELETE</code>.  All the columns from the <code class="literal">films</code> table will326   be updatable, whereas the computed columns <code class="literal">country</code> and327   <code class="literal">avg_rating</code> will be read-only.328  </p><p>329   Create a recursive view consisting of the numbers from 1 to 100:330</p><pre class="programlisting">331CREATE RECURSIVE VIEW public.nums_1_100 (n) AS332    VALUES (1)333UNION ALL334    SELECT n+1 FROM nums_1_100 WHERE n &lt; 100;335</pre><p>336   Notice that although the recursive view's name is schema-qualified in this337   <code class="command">CREATE</code>, its internal self-reference is not schema-qualified.338   This is because the implicitly-created CTE's name cannot be339   schema-qualified.340  </p></div><div class="refsect1" id="id-1.9.3.97.9"><h2>Compatibility</h2><p>341   <code class="command">CREATE OR REPLACE VIEW</code> is a342   <span class="productname">PostgreSQL</span> language extension.343   So is the concept of a temporary view.344   The <code class="literal">WITH ( ... )</code> clause is an extension as well, as are345   security barrier views and security invoker views.346  </p></div><div class="refsect1" id="id-1.9.3.97.10"><h2>See Also</h2><span class="simplelist"><a class="xref" href="sql-alterview.html" title="ALTER VIEW"><span class="refentrytitle">ALTER VIEW</span></a>, <a class="xref" href="sql-dropview.html" title="DROP VIEW"><span class="refentrytitle">DROP VIEW</span></a>, <a class="xref" href="sql-creatematerializedview.html" title="CREATE MATERIALIZED VIEW"><span class="refentrytitle">CREATE MATERIALIZED VIEW</span></a></span></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="sql-createusermapping.html" title="CREATE USER MAPPING">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="sql-commands.html" title="SQL Commands">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="sql-deallocate.html" title="DEALLOCATE">Next</a></td></tr><tr><td width="40%" align="left" valign="top">CREATE USER MAPPING </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="40%" align="right" valign="top"> DEALLOCATE</td></tr></table></div></body></html>
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