inventory management system in windows Form c#

Question

how to create Stock Table form  Sell Table & Purchase Table

 

Sell_Table

Date	Bill No	Product Name	Unit	Qty	Rate	Total Amount
25/11/2017	13	Notebook	Pic	100	10	1000
25/11/2017	12	Keyboard	Pic	10	300	3000
25/10/2017	11	Mobile	Pic	5	5000	25000
10/10/20 17	10	Keyboard	Pic	20	300	6000
5/8/2017	9	Mobile	Pic	10	500	5000

Purchase_Table

Date	Product Name	Unit	Qty	Rate	Total Amount
5/11/2017	Notebook	Pic	500	10	5000
25/10/2017	Keyboard	Pic	100	300	30000
25/10/2017	Mobile	Pic	10	5000	50000
10/10/2017	Keyboard	Pic	20	300	6000
5/8/2017	Mobile	Pic	100	500	50000

Stock_Table

Month	Product Name	Unit	Opening_Balance	TotalSold	Closing_Balance
Nov. 2017	Notebook	Pic	500	100	400
Nov. 2017	Keyboard	Pic	100	10	90
Oct 2017	Keyboard	Pic	20+100=120	20	100
Oct 2017	Mobile	Pic	90+10 = 100	5	95
Aug 2017	Mobile	Pic	100	10	90