The function "Length" allows to determine the length of objects which are present in a table, via the field "the_geom".

Syntax : select ST_Length(the_geom) from myTable;

Example :

       - Goal : Calculate the sum of the lengthes of the hydrographic sections

       - Syntax : select Sum(ST_Length(the_geom)) as Longueur from "TRONCON_HYDROGRAPHIQUE";

       - Result : we obtain an alphanumeric value


Remarks :

       - The first operator Length calculate the length of every geometry. The identifier the_geom corresponds to the column which contains the geometry of objects. Note that this identifier is necessary for all spatial functions.

       - The second operator Sum is an aggregated alphanumeric function which calculate the global length - > the total - > the sum.

Copyright - IRSTV - 2009 - www.orbisgis.org