[postgis-users] SUM() for lines

[Daniel Grum]

Hi all,

how can I sum the atributes of any lines of one column --> how I can sum 
the info of a column.
I want to save all avaible resources(all polygons) in an extra column 
next to the resources of one polygon?!

like this:
gid(integer) | flaeche(double precision) | sum_flaeche(double precision)
   1                            
2000                                      2000
   2                            
5000                                      7000
   3                             
100                                       7100

And how I can select the last info of the column: sum_flaeche to wok 
with the number-->in this case: 7100

If this could not work please describe me another possible way?!

--daniel