<!-- $PostgreSQL: pgsql/doc/src/sgml/information_schema.sgml,v 1.31 2007/02/01 00:28:17 momjian Exp $ -->

<!-- $PostgreSQL: pgsql/doc/src/sgml/information_schema.sgml,v 1.32 2007/02/20 18:47:25 momjian Exp $ -->

<chapter id="information-schema">

<title>The Information Schema</title>

SELECT c.column_name, c.data_type, e.data_type AS element_type

FROM information_schema.columns c LEFT JOIN information_schema.element_types e

ON ((c.table_catalog, c.table_schema, c.table_name, 'TABLE', c.dtd_identifier)

= (e.object_catalog, e.object_schema, e.object_name, e.object_type, e.array_type_identifier))

= (e.object_catalog, e.object_schema, e.object_name, e.object_type, e.dtd_identifier))

WHERE c.table_schema = '...' AND c.table_name = '...'

ORDER BY c.ordinal_position;

</programlisting>

</row>

<row>

<entry><literal>array_type_identifier</literal></entry>

<entry><literal>dtd_identifier</literal></entry>

<entry><type>sql_identifier</type></entry>

<entry>

The identifier of the data type descriptor of the array being

described. Use this to join with the

<literal>dtd_identifier</literal> columns of other information

schema views.

described

</entry>

</row>

<entry>Always null, because arrays always have unlimited maximum cardinality in <productname>PostgreSQL</></entry>

</row>

<row>

<entry><literal>dtd_identifier</literal></entry>

<entry><type>sql_identifier</type></entry>

<entry>

An identifier of the data type descriptor of the element. This

is currently not useful.

</entry>

</row>

</tbody>

</tgroup>