Create table with substrackt values

[r_vdbraak]

Hello all,

I'm having a table with date (Datum) and a value (Stand).

Datum	Stand	Verbruik
31-12-2013	1883
28-2-2014	2281	398
30-4-2014	2577	296
24-6-2014	2767	190

What I need is to add a column named Verbruik, containing the difference between Stand and Stand of the Previous Datum.

I hope sombody can help me.

[alexandros17 · Accepted solution]

order by datum then use this expression

sum(Stand)-Above(Stand)