Comparing records within an internal table

Hi,

I have to compare records within an ITAB.

eg

ITAB

Field1 Field2 Field3 Field4

Abc 06 Xyz 100

Def 05 Xyz 25

I have to compare the records withing this ITAB

If field1 & 3 are same in two records and field2 is different in the same two records, then I have to subract the fourth fields ..

Please let me know how can I code this? I'm confused..

Thanks..

Uma.

Message was edited by:

Uma