On Mon, Dec 22, 2003 at 04:54:01PM +0800, Daniel Lau wrote:
> I am wondering if we are able to extract the x-coordinate from a
> point-type attribute with SQL. I have been looking for this sort of
> functions from documents and websites but it seems the function does not
> exist. Or, any altnernate to do so?
From the bottom of the Geometric Functions and Operators chapter of
the documentation:
"It is possible to access the two component numbers of a point as
though it were an array with indices 0 and 1. For example, if t.p
is a point column then SELECT p[0] FROM t retrieves the X coordinate
and UPDATE t SET p[1] = ... changes the Y coordinate. In the same way,
a value of type box or lseg may be treated as an array of two point
values."
http://www.postgresql.org/docs/current/static/functions-geometry.html
--
Michael Fuhr
http://www.fuhr.org/~mfuhr/