information_schema.sgml

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

     <row>
      <entry><literal>is_grantable</literal></entry>
      <entry><type>character_data</type></entry>
      <entry><literal>YES</literal> if the privilege is grantable, <literal>NO</literal> if not</entry>
     </row>
    </tbody>
   </tgroup>
  </table>

  <para>
   Note that the column <literal>grantee</literal> makes no
   distinction between users and groups.  If you have users and groups
   with the same name, there is unfortunately no way to distinguish
   them.  A future version of <productname>PostgreSQL</productname>
   will possibly prohibit having users and groups with the same name.
  </para>
 </sect1>

 <sect1 id="infoschema-column-udt-usage">
  <title><literal>column_udt_usage</literal></title>

  <para>
   The view <literal>column_udt_usage</literal> identifies all columns
   that use data types owned by the current user.  Note that in
   <productname>PostgreSQL</productname>, built-in data types behave
   like user-defined types, so they are included here as well.  See
   also <xref linkend="infoschema-columns"> for details.
  </para>

  <table>
   <title><literal>column_udt_usage</literal> Columns</title>

   <tgroup cols="3">
    <thead>
     <row>
      <entry>Name</entry>
      <entry>Data Type</entry>
      <entry>Description</entry>
     </row>
    </thead>

    <tbody>
     <row>
      <entry><literal>udt_catalog</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>
       Name of the database that the column data type (the underlying
       type of the domain, if applicable) is defined in (always the
       current database)
      </entry>
     </row>

     <row>
      <entry><literal>udt_schema</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>
       Name of the schema that the column data type (the underlying
       type of the domain, if applicable) is defined in
      </entry>
     </row>

     <row>
      <entry><literal>udt_name</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>
       Name of the column data type (the underlying type of the
       domain, if applicable)
      </entry>
     </row>

     <row>
      <entry><literal>table_catalog</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Name of the database containing the table (always the current database)</entry>
     </row>

     <row>
      <entry><literal>table_schema</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Name of the schema containing the table</entry>
     </row>

     <row>
      <entry><literal>table_name</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Name of the table</entry>
     </row>

     <row>
      <entry><literal>column_name</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Name of the column</entry>
     </row>
    </tbody>
   </tgroup>
  </table>
 </sect1>

 <sect1 id="infoschema-columns">
  <title><literal>columns</literal></title>

  <para>
   The view <literal>columns</literal> contains information about all
   table columns (or view columns) in the database.  System columns
   (<literal>oid</>, etc.) are not included.  Only those columns are
   shown that the current user has access to (by way of being the
   owner or having some privilege).
  </para>

  <table>
   <title><literal>columns</literal> Columns</title>

   <tgroup cols="3">
    <thead>
     <row>
      <entry>Name</entry>
      <entry>Data Type</entry>
      <entry>Description</entry>
     </row>
    </thead>

    <tbody>
     <row>
      <entry><literal>table_catalog</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Name of the database containing the table (always the current database)</entry>
     </row>

     <row>
      <entry><literal>table_schema</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Name of the schema containing the table</entry>
     </row>

     <row>
      <entry><literal>table_name</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Name of the table</entry>
     </row>

     <row>
      <entry><literal>column_name</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Name of the column</entry>
     </row>

     <row>
      <entry><literal>ordinal_position</literal></entry>
      <entry><type>cardinal_number</type></entry>
      <entry>Ordinal position of the column within the table (count starts at 1)</entry>
     </row>

     <row>
      <entry><literal>column_default</literal></entry>
      <entry><type>character_data</type></entry>
      <entry>
       Default expression of the column (null if the current user is
       not the owner of the table containing the column)
      </entry>
     </row>

     <row>
      <entry><literal>is_nullable</literal></entry>
      <entry><type>character_data</type></entry>
      <entry>
       <literal>YES</literal> if the column is possibly nullable,
       <literal>NO</literal> if it is known not nullable.  A not-null
       constraint is one way a column can be known not nullable, but
       there may be others.
      </entry>
     </row>

     <row>
      <entry><literal>data_type</literal></entry>
      <entry><type>character_data</type></entry>
      <entry>
       Data type of the column, if it is a built-in type, or
       <literal>ARRAY</literal> if it is some array (in that case, see
       the view <literal>element_types</literal>), else
       <literal>USER-DEFINED</literal> (in that case, the type is
       identified in <literal>udt_name</literal> and associated
       columns).  If the column is based on a domain, this column
       refers to the type underlying the domain (and the domain is
       identified in <literal>domain_name</literal> and associated
       columns).
      </entry>
     </row>

     <row>
      <entry><literal>character_maximum_length</literal></entry>
      <entry><type>cardinal_number</type></entry>
      <entry>
       If <literal>data_type</literal> identifies a character or bit
       string type, the declared maximum length; null for all other
       data types or if no maximum length was declared.
      </entry>
     </row>

     <row>
      <entry><literal>character_octet_length</literal></entry>
      <entry><type>cardinal_number</type></entry>
      <entry>
       If <literal>data_type</literal> identifies a character type,
       the maximum possible length in octets (bytes) of a datum (this
       should not be of concern to <productname>PostgreSQL</productname> users); null for all
       other data types.
      </entry>
     </row>

     <row>
      <entry><literal>numeric_precision</literal></entry>
      <entry><type>cardinal_number</type></entry>
      <entry>
       If <literal>data_type</literal> identifies a numeric type, this
       column contains the (declared or implicit) precision of the
       type for this column.  The precision indicates the number of
       significant digits.  It may be expressed in decimal (base 10)
       or binary (base 2) terms, as specified in the column
       <literal>numeric_precision_radix</literal>.  For all other data
       types, this column is null.
      </entry>
     </row>

     <row>
      <entry><literal>numeric_precision_radix</literal></entry>
      <entry><type>cardinal_number</type></entry>
      <entry>
       If <literal>data_type</literal> identifies a numeric type, this
       column indicates in which base the values in the columns
       <literal>numeric_precision</literal> and
       <literal>numeric_scale</literal> are expressed.  The value is
       either 2 or 10.  For all other data types, this column is null.
      </entry>
     </row>

     <row>
      <entry><literal>numeric_scale</literal></entry>
      <entry><type>cardinal_number</type></entry>
      <entry>
       If <literal>data_type</literal> identifies an exact numeric
       type, this column contains the (declared or implicit) scale of
       the type for this column.  The scale indicates the number of
       significant digits to the right of the decimal point.  It may
       be expressed in decimal (base 10) or binary (base 2) terms, as
       specified in the column
       <literal>numeric_precision_radix</literal>.  For all other data
       types, this column is null.
      </entry>
     </row>

     <row>
      <entry><literal>datetime_precision</literal></entry>
      <entry><type>cardinal_number</type></entry>
      <entry>
       If <literal>data_type</literal> identifies a date, time, or
       interval type, the declared precision; null for all other data
       types or if no precision was declared.
      </entry>
     </row>

     <row>
      <entry><literal>interval_type</literal></entry>
      <entry><type>character_data</type></entry>
      <entry>Not yet implemented</entry>
     </row>

     <row>
      <entry><literal>interval_precision</literal></entry>
      <entry><type>character_data</type></entry>
      <entry>Not yet implemented</entry>
     </row>

     <row>
      <entry><literal>character_set_catalog</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>character_set_schema</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>character_set_name</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>collation_catalog</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>collation_schema</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>collation_name</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>domain_catalog</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>
       If the column has a domain type, the name of the database that
       the domain is defined in (always the current database), else
       null.
      </entry>
     </row>

     <row>
      <entry><literal>domain_schema</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>
       If the column has a domain type, the name of the schema that
       the domain is defined in, else null.
      </entry>
     </row>

     <row>
      <entry><literal>domain_name</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>If the column has a domain type, the name of the domain, else null.</entry>
     </row>

     <row>
      <entry><literal>udt_catalog</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>
       Name of the database that the column data type (the underlying
       type of the domain, if applicable) is defined in (always the
       current database)
      </entry>
     </row>

     <row>
      <entry><literal>udt_schema</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>
       Name of the schema that the column data type (the underlying
       type of the domain, if applicable) is defined in
      </entry>
     </row>

     <row>
      <entry><literal>udt_name</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>
       Name of the column data type (the underlying type of the
       domain, if applicable)
      </entry>
     </row>

     <row>
      <entry><literal>scope_catalog</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>scope_schema</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>scope_name</literal></entry>
      <entry><type>sql_identifier</type></entry>
      <entry>Applies to a feature not available in <productname>PostgreSQL</></entry>
     </row>

     <row>
      <entry><literal>maximum_cardinality</literal></entry>
      <entry><type>cardinal_number</type></entry>
      <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 column, unique
       among the data type descriptors pertaining to the table.  This
       is mainly useful for joining with other instances of such
       identifiers.  (The specific format of the identifier is not
       defined and not guaranteed to remain the same in future
       versions.)
      </entry>