doc/src/sgml/ref/drop_table.sgml - master - githubmirror/postgres

doc/src/sgml/ref/drop_table.sgml
129 строк3 KB
Peter Eisentraut
Improve <xref> vs. <command> formatting in the documentation
03 окт 2020, 17:40
03 окт 2020, 17:409081bdd
<!--
doc/src/sgml/ref/drop_table.sgml
PostgreSQL documentation
-->

<refentry id="sql-droptable">
 <indexterm zone="sql-droptable">
  <primary>DROP TABLE</primary>
 </indexterm>

 <refmeta>
  <refentrytitle>DROP TABLE</refentrytitle>
  <manvolnum>7</manvolnum>
  <refmiscinfo>SQL - Language Statements</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>DROP TABLE</refname>
  <refpurpose>remove a table</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
<synopsis>
DROP TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable> [, ...] [ CASCADE | RESTRICT ]
</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <command>DROP TABLE</command> removes tables from the database.
   Only the table owner, the schema owner, and superuser can drop a
   table.  To empty a table of rows
   without destroying the table, use <link linkend="sql-delete"><command>DELETE</command></link>
   or <link linkend="sql-truncate"><command>TRUNCATE</command></link>.
  </para>

  <para>
   <command>DROP TABLE</command> always removes any indexes, rules,
   triggers, and constraints that exist for the target table.
   However, to drop a table that is referenced by a view or a foreign-key
   constraint of another table, <literal>CASCADE</literal> must be
   specified. (<literal>CASCADE</literal> will remove a dependent view entirely,
   but in the foreign-key case it will only remove the foreign-key
   constraint, not the other table entirely.)
  </para>
 </refsect1>

 <refsect1>
  <title>Parameters</title>

  <variablelist>
   <varlistentry>
    <term><literal>IF EXISTS</literal></term>
    <listitem>
     <para>
      Do not throw an error if the table does not exist. A notice is issued
      in this case.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">name</replaceable></term>
    <listitem>
     <para>
      The name (optionally schema-qualified) of the table to drop.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><literal>CASCADE</literal></term>
    <listitem>
     <para>
      Automatically drop objects that depend on the table (such as
      views),
      and in turn all objects that depend on those objects
      (see <xref linkend="ddl-depend"/>).
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><literal>RESTRICT</literal></term>
    <listitem>
     <para>
      Refuse to drop the table if any objects depend on it.  This is
      the default.
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1>
  <title>Examples</title>

  <para>
   To destroy two tables, <literal>films</literal> and
   <literal>distributors</literal>:

<programlisting>
DROP TABLE films, distributors;
</programlisting></para>
 </refsect1>

 <refsect1>
  <title>Compatibility</title>

  <para>
   This command conforms to the SQL standard, except that the standard only
   allows one table to be dropped per command, and apart from the
   <literal>IF EXISTS</literal> option, which is a <productname>PostgreSQL</productname>
   extension.
  </para>
 </refsect1>

 <refsect1>
  <title>See Also</title>

  <simplelist type="inline">
   <member><xref linkend="sql-altertable"/></member>
   <member><xref linkend="sql-createtable"/></member>
  </simplelist>
 </refsect1>

</refentry>