Help on doing difference of dates with prev row.

[vega83]

Friends I have data like below

TICK: user time
A1 D1 12/30/2009
A1 D2 12/31//2009
A1 D2 01/01/2010

A3 D1 01/01/2010
A3 D2 01/02/2010
A3 D2 01/03/2010

I wold like to do date diff with prev colum and want to display data like below

TICK: user time datediff
A1 D1 12/30/2009 0
A1 D2 12/31//2009 1
A1 D2 01/01/2010 1

A3 D1 01/01/2010 0
A3 D2 01/02/2010 1
A3 D2 01/04/2010 2

Any help on this?
Thanks,
Vega

 

[lbass]

if onfirstrecord or
{table.tick} <> previous({table.tick}) then
0 else
datediff("d",previous({table.date}),{table.date})

-LB