Existing I have the following table structure (in Excel) and now want to have
better control by using ACCESS.

SC no Buyer PC no Supplier Item QTY price cost
SC001 A Co PC501 H co SS 70 30 28
SC001 A Co PC501 H co CC 100 25 21
SC001 A Co PC502 Q co BB 20 90 80
SC001 A Co PC503 J co SS 50 31 27

remark :
SC no = sale contract number
PC no = purchase onctract number
Relationship b/w SC & PC is 1 to many
SC & PC will arise at the same time (no inventory base)

How to design my tables (in Access) so that I can handle this?
The main problem I meet is the duplicate input for SC & PC for the same
items & need to separate it one-by-one as per above table.