doc/src/sgml/ref/drop_type.sgml

   1 <!--
   2 $PostgreSQL$
   3 PostgreSQL documentation
   4 -->
   5
   6 <refentry id="SQL-DROPTYPE">
   7  <refmeta>
   8   <refentrytitle id="SQL-DROPTYPE-TITLE">DROP TYPE</refentrytitle>
   9   <refmiscinfo>SQL - Language Statements</refmiscinfo>
  10  </refmeta>
  11
  12  <refnamediv>
  13   <refname>DROP TYPE</refname>
  14   <refpurpose>remove a data type</refpurpose>
  15  </refnamediv>
  16
  17  <indexterm zone="sql-droptype">
  18   <primary>DROP TYPE</primary>
  19  </indexterm>
  20
  21  <refsynopsisdiv>
  22 <synopsis>
  23 DROP TYPE [ IF EXISTS ] <replaceable class="PARAMETER">name</replaceable> [, ...] [ CASCADE | RESTRICT ]
  24 </synopsis>
  25  </refsynopsisdiv>
  26
  27  <refsect1>
  28   <title>Description</title>
  29
  30   <para>
  31    <command>DROP TYPE</command> removes a user-defined data type.
  32    Only the owner of a type can remove it.
  33   </para>
  34  </refsect1>
  35
  36  <refsect1>
  37   <title>Parameters</title>
  38
  39   <variablelist>
  40    <varlistentry>
  41     <term><literal>IF EXISTS</literal></term>
  42     <listitem>
  43      <para>
  44       Do not throw an error if the type does not exist. A notice is issued
  45       in this case.
  46      </para>
  47     </listitem>
  48    </varlistentry>
  49
  50    <varlistentry>
  51     <term><replaceable class="PARAMETER">name</replaceable></term>
  52     <listitem>
  53      <para>
  54       The name (optionally schema-qualified) of the data type to remove.
  55      </para>
  56     </listitem>
  57    </varlistentry>
  58
  59    <varlistentry>
  60     <term><literal>CASCADE</literal></term>
  61     <listitem>
  62      <para>
  63       Automatically drop objects that depend on the type (such as
  64       table columns, functions, operators).
  65      </para>
  66     </listitem>
  67    </varlistentry>
  68
  69    <varlistentry>
  70     <term><literal>RESTRICT</literal></term>
  71     <listitem>
  72      <para>
  73       Refuse to drop the type if any objects depend on it.  This is
  74       the default.
  75      </para>
  76     </listitem>
  77    </varlistentry>
  78   </variablelist>
  79  </refsect1>
  80
  81  <refsect1 id="SQL-DROPTYPE-examples">
  82   <title>Examples</title>
  83
  84   <para>
  85    To remove the data type <type>box</type>:
  86 <programlisting>
  87 DROP TYPE box;
  88 </programlisting>
  89   </para>
  90  </refsect1>
  91
  92  <refsect1 id="SQL-DROPTYPE-compatibility">
  93   <title>Compatibility</title>
  94
  95   <para>
  96    This command is similar to the corresponding command in the SQL
  97    standard, apart from the <literal>IF EXISTS</>
  98    option, which is a <productname>PostgreSQL</> extension.
  99    But note that the <command>CREATE TYPE</command> command
 100    and the data type extension mechanisms in
 101    <productname>PostgreSQL</productname> differ from the SQL standard.
 102   </para>
 103  </refsect1>
 104
 105  <refsect1 id="SQL-DROPTYPE-see-also">
 106   <title>See Also</title>
 107
 108   <simplelist type="inline">
 109    <member><xref linkend="sql-createtype" endterm="sql-createtype-title"></member>
 110    <member><xref linkend="sql-altertype" endterm="sql-altertype-title"></member>
 111   </simplelist>
 112  </refsect1>
 113
 114 </refentry>