I have a table with the fields CodCliente, CodProd and Fecha.
I want to subtract the last value to the penultimate Fecha group by CodCliente and CodProd and next make the average of the substract.
This is the table:
CodCliente
CodProd
Fecha
1
1
30/04/2012
1
1
07/05/2012
1
1
15/05/2012
1
2
26/05/2012
1
2
18/06/2012
2
1
02/07/2012
2
1
25/08/2012
2
1
09/10/2012
2
2
15/10/2012
2
2
23/10/2012
2
2
02/11/2012
2
2
14/11/2012
I need substract for the CodCliente 1 and CodProd 1 15/05/2012 - 07/05/2012 and next substract for the CodCliente 1 and CodProd 2 18/06/2012 - 26/05/2012 and calculate de average of this.
