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<!--
doc/src/sgml/ref/create_schema.sgml
PostgreSQL documentation
-->
<refentry id="sql-createschema">
<indexterm zone="sql-createschema">
<primary>CREATE SCHEMA</primary>
</indexterm>
<refmeta>
<refentrytitle>CREATE SCHEMA</refentrytitle>
<manvolnum>7</manvolnum>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>CREATE SCHEMA</refname>
<refpurpose>define a new schema</refpurpose>
</refnamediv>
<refsynopsisdiv>
<synopsis>
CREATE SCHEMA <replaceable class="parameter">schema_name</replaceable> [ AUTHORIZATION <replaceable class="parameter">role_specification</replaceable> ] [ <replaceable class="parameter">schema_element</replaceable> [ ... ] ]
CREATE SCHEMA AUTHORIZATION <replaceable class="parameter">role_specification</replaceable> [ <replaceable class="parameter">schema_element</replaceable> [ ... ] ]
CREATE SCHEMA IF NOT EXISTS <replaceable class="parameter">schema_name</replaceable> [ AUTHORIZATION <replaceable class="parameter">role_specification</replaceable> ]
CREATE SCHEMA IF NOT EXISTS AUTHORIZATION <replaceable class="parameter">role_specification</replaceable>
<phrase>where <replaceable class="parameter">role_specification</replaceable> can be:</phrase>
<replaceable class="parameter">user_name</replaceable>
| CURRENT_ROLE
| CURRENT_USER
| SESSION_USER
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>CREATE SCHEMA</command> enters a new schema
into the current database.
The schema name must be distinct from the name of any existing schema
in the current database.
</para>
<para>
A schema is essentially a namespace:
it contains named objects (tables, data types, functions, and operators)
whose names can duplicate those of other objects existing in other
schemas. Named objects are accessed either by <quote>qualifying</quote>
their names with the schema name as a prefix, or by setting a search
path that includes the desired schema(s). A <literal>CREATE</literal> command
specifying an unqualified object name creates the object
in the current schema (the one at the front of the search path,
which can be determined with the function <function>current_schema</function>).
</para>
<para>
Optionally, <command>CREATE SCHEMA</command> can include subcommands
to create objects within the new schema. The subcommands are treated
essentially the same as separate commands issued after creating the
schema, except that if the <literal>AUTHORIZATION</literal> clause is used,
all the created objects will be owned by that user.
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><replaceable class="parameter">schema_name</replaceable></term>
<listitem>
<para>
The name of a schema to be created. If this is omitted, the
<replaceable class="parameter">user_name</replaceable>
is used as the schema name. The name cannot
begin with <literal>pg_</literal>, as such names
are reserved for system schemas.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">user_name</replaceable></term>
<listitem>
<para>
The role name of the user who will own the new schema. If omitted,
defaults to the user executing the command. To create a schema
owned by another role, you must be able to
<literal>SET ROLE</literal> to that role.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">schema_element</replaceable></term>
<listitem>
<para>
An SQL statement defining an object to be created within the
schema. Currently, only <command>CREATE
TABLE</command>, <command>CREATE VIEW</command>, <command>CREATE
INDEX</command>, <command>CREATE SEQUENCE</command>, <command>CREATE
TRIGGER</command> and <command>GRANT</command> are accepted as clauses
within <command>CREATE SCHEMA</command>. Other kinds of objects may
be created in separate commands after the schema is created.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>IF NOT EXISTS</literal></term>
<listitem>
<para>
Do nothing (except issuing a notice) if a schema with the same name
already exists. <replaceable class="parameter">schema_element</replaceable>
subcommands cannot be included when this option is used.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<para>
To create a schema, the invoking user must have the
<literal>CREATE</literal> privilege for the current database.
(Of course, superusers bypass this check.)
</para>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
Create a schema:
<programlisting>
CREATE SCHEMA myschema;
</programlisting>
</para>
<para>
Create a schema for user <literal>joe</literal>; the schema will also be
named <literal>joe</literal>:
<programlisting>
CREATE SCHEMA AUTHORIZATION joe;
</programlisting>
</para>
<para>
Create a schema named <literal>test</literal> that will be owned by user
<literal>joe</literal>, unless there already is a schema named <literal>test</literal>.
(It does not matter whether <literal>joe</literal> owns the pre-existing schema.)
<programlisting>
CREATE SCHEMA IF NOT EXISTS test AUTHORIZATION joe;
</programlisting>
</para>
<para>
Create a schema and create a table and view within it:
<programlisting>
CREATE SCHEMA hollywood
CREATE TABLE films (title text, release date, awards text[])
CREATE VIEW winners AS
SELECT title, release FROM films WHERE awards IS NOT NULL;
</programlisting>
Notice that the individual subcommands do not end with semicolons.
</para>
<para>
The following is an equivalent way of accomplishing the same result:
<programlisting>
CREATE SCHEMA hollywood;
CREATE TABLE hollywood.films (title text, release date, awards text[]);
CREATE VIEW hollywood.winners AS
SELECT title, release FROM hollywood.films WHERE awards IS NOT NULL;
</programlisting></para>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para>
The SQL standard allows a <literal>DEFAULT CHARACTER SET</literal> clause
in <command>CREATE SCHEMA</command>, as well as more subcommand
types than are presently accepted by
<productname>PostgreSQL</productname>.
</para>
<para>
The SQL standard specifies that the subcommands in <command>CREATE
SCHEMA</command> can appear in any order. The present
<productname>PostgreSQL</productname> implementation does not
handle all cases of forward references in subcommands; it might
sometimes be necessary to reorder the subcommands in order to avoid
forward references.
</para>
<para>
According to the SQL standard, the owner of a schema always owns
all objects within it. <productname>PostgreSQL</productname>
allows schemas to contain objects owned by users other than the
schema owner. This can happen only if the schema owner grants the
<literal>CREATE</literal> privilege on their schema to someone else, or a
superuser chooses to create objects in it.
</para>
<para>
The <literal>IF NOT EXISTS</literal> option is a
<productname>PostgreSQL</productname> extension.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<simplelist type="inline">
<member><xref linkend="sql-alterschema"/></member>
<member><xref linkend="sql-dropschema"/></member>
</simplelist>
</refsect1>
</refentry>
|
