Passing a calculated value from one record to the next one in the same table

[RiVit]

I have a table with product purchases (Oper_dia), and when I sell (Oper_SocInv) I have to do with First In First Out (FIFO), and the quantity sold (opsi_titulos), is not identical to a purchase, so that have to sell the first purchase and the remaining cover with the second purchase, and if there are remaining with the third purchase, and so on
In the next image (form F_Oper_SocInv), you could see the inventory of the product, and the detail of each buy, also I have another subform with the sell operation (Operación).



With “Integra operaciones” I declare a global variable var1, and open the query Act_Oper_dia


With the global variable I can calculate the values ​​for the first record, but I can not pass values ​​to the second record, by updating the value of var1, or any other method.

Act_Oper_dia
Fecha	Títulos	Precio	Importe	Tit_vta	var1	Fecha Cmp
21/03/2012	-615.00	-29.16		-615	-6715	02/03/2012
21/03/2012	-16,389.00	-29.16		-7330	0	05/03/2012
23/03/2012	-52.00	-29.16		-52	-7278	08/03/2012

I need the follow result, where Tit_vta are the quantity sale by each previus buy

opd_fecha	opd_titulos	Precio	opd_prec	opd_impte	Tit_vta	var1
21/03/2012	-615	-29.1562	0		-615	-6715
21/03/2012	-16389	-29.1562	0		-6715	0
23/03/2012	-52	-29.1562	0		0	0

I send you the application

I appreciate your help

[June7]

If I understand correctly, this is a 'running sum'. Textbox on report has a RunningSum property. No so easy to do on a form. Review http://us.generation-nt.com/answer/h...-15715012.html