diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index aed47db79b92de57db3e615c234429b100ceed9c..8d722a91853ece180cd4e7092040bb0142d46a27 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -1,5 +1,5 @@ <!-- -$Header: /cvsroot/pgsql/doc/src/sgml/func.sgml,v 1.108 2002/08/06 05:40:44 ishii Exp $ +$Header: /cvsroot/pgsql/doc/src/sgml/func.sgml,v 1.109 2002/08/08 14:29:07 tgl Exp $ PostgreSQL documentation --> @@ -3868,7 +3868,7 @@ SELECT TIMESTAMP 'now'; </row> <row> <entry> # </entry> - <entry>Number of points in polygon</entry> + <entry>Number of points in path or polygon</entry> <entry><literal># '((1,0),(0,1),(-1,0))'</literal></entry> </row> <row> @@ -4025,6 +4025,18 @@ SELECT TIMESTAMP 'now'; <entry>length of item</entry> <entry><literal>length(path '((-1,0),(1,0))')</literal></entry> </row> + <row> + <entry><function>npoints</function>(path)</entry> + <entry><type>integer</type></entry> + <entry>number of points</entry> + <entry><literal>npoints(path '[(0,0),(1,1),(2,0)]')</literal></entry> + </row> + <row> + <entry><function>npoints</function>(polygon)</entry> + <entry><type>integer</type></entry> + <entry>number of points</entry> + <entry><literal>npoints(polygon '((1,1),(0,0))')</literal></entry> + </row> <row> <entry><function>pclose</function>(path)</entry> <entry><type>path</type></entry> @@ -4040,12 +4052,6 @@ SELECT TIMESTAMP 'now'; <entry><literal>point(lseg '((-1,0),(1,0))',lseg '((-2,-2),(2,2))')</literal></entry> </row> ]]> - <row> - <entry><function>npoint</function>(path)</entry> - <entry><type>integer</type></entry> - <entry>number of points</entry> - <entry><literal>npoints(path '[(0,0),(1,1),(2,0)]')</literal></entry> - </row> <row> <entry><function>popen</function>(path)</entry> <entry><type>path</type></entry> @@ -4150,7 +4156,7 @@ SELECT TIMESTAMP 'now'; <row> <entry><function>polygon</function>(<type>box</type>)</entry> <entry><type>polygon</type></entry> - <entry>12 point polygon</entry> + <entry>4-point polygon</entry> <entry><literal>polygon(box '((0,0),(1,1))')</literal></entry> </row> <row> @@ -4175,6 +4181,16 @@ SELECT TIMESTAMP 'now'; </tgroup> </table> + <para> + It is possible to access the two component numbers of a <type>point</> + as though it were an array with subscripts 0,1. For example, if + <literal>t.p</> is a <type>point</> column then + <literal>SELECT p[0] FROM t</> retrieves the X coordinate; + <literal>UPDATE t SET p[1] = ...</> changes the Y coordinate. + In the same way, a <type>box</> or an <type>lseg</> may be treated + as an array of two <type>point</>s. + </para> + </sect1>