Just could not work this one out. Hope some one could help.
I want to build a query which returns a rolling subtraction on a walue. eg.
Object. Value. Roling subtraction
Ruler 5 0
Rubber 3 2
Pen 4 -1
Ink 1 3
So the roling subtraction needs to get the value from the previou record of the query. What I can not work out is how to get a statement to point to the previous record, so it says something like.
(Value of previous record - current value).
Anyone know how to do this? Thanks.
I want to build a query which returns a rolling subtraction on a walue. eg.
Object. Value. Roling subtraction
Ruler 5 0
Rubber 3 2
Pen 4 -1
Ink 1 3
So the roling subtraction needs to get the value from the previou record of the query. What I can not work out is how to get a statement to point to the previous record, so it says something like.
(Value of previous record - current value).
Anyone know how to do this? Thanks.