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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2002-08-08 14:29:07 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2002-08-08 14:29:07 +0000 |
| commit | d176fad58059b7e652998a37da5cb9788ec7ea40 (patch) | |
| tree | 99b6d3edb00aaf369b02a274c36f4257bf3e236c /doc/src | |
| parent | f84002176f3f4d52fb1dad13a725967ca4974853 (diff) | |
| download | postgresql-d176fad58059b7e652998a37da5cb9788ec7ea40.tar.gz postgresql-d176fad58059b7e652998a37da5cb9788ec7ea40.zip | |
Some improvements in geometric-operators documentation.
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/func.sgml | 34 |
1 files changed, 25 insertions, 9 deletions
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index aed47db79b9..8d722a91853 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> @@ -4026,6 +4026,18 @@ SELECT TIMESTAMP 'now'; <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> <entry>convert path to closed</entry> @@ -4041,12 +4053,6 @@ SELECT TIMESTAMP 'now'; </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> <entry>convert path to open path</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> |