How to get Difference of a two Records of Same Colums Sum

[#1]

I am Having Data Like Following..

DataBase	STORE CCODE	GROSS	DISCOUNT
CO	12250	122855120	600215
ReSA	12250	122855120	600215
CO	13521	234821232	552310
ReSA	13521	234821232	552310

I want to Show the Difference of GROSS between two DataBases for particular Store, as well as for DISCOUNT also.

Please help me to get this.

[Gysbert_Wassenaar]

How about: max(GROSS)-min(GROSS)