[postgis-users] distance between two end points of a line

[temiz]

hello

I want to calculate distance between two end points of a line

I used:
select cat, 
distance(pointn(wkb_geometry,1),pointn(wkb_geometry,npoints(wkb_geometry))) 
from spelhey;

it gives all zero

 cat | distance
-----+----------
   1 |        0
   2 |        0
   3 |        0
   4 |        0
   5 |        0
   6 |        0
   7 |        0
   8 |        0
   9 |        0
  10 |        0
  11 |        0
  12 |        0
  13 |        0
  14 |        0
  15 |        0
  16 |        0
  17 |        0
  17 |        0

can you tell me what happened ?

regards


-- 
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.