How to store multiple purchased item with one client in SQL server(invoice generation and storing in SQL database)

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C#3.5

i am generating invoice. i am stuck in maintaining that table. i have purchased product in gridview.(which can be more than one) and other common fields are (client name,Due date,Issue date) then i am calculating that items price with discount and shipping charge outside the datagridview.

in short ,i am storing items with their unit price and quantity in one table.
and total of all purchased items with discount,shiping charge on that total i am storing in another table.

now i am facing problem in generating rdlc report.becasue it takes only one table.(i have two. i.e saleproduct and main table)

now i am confused how to show final invoice with rdlc report.

What I have tried:

these are my tables:
saleproduct:
Product_Name,
Description,
Unit_Price,
Qty,
Total,
Tax,
TotalwithTax

2)Main table:
MainId,
Client_Name
Billing_Address,
Shipping_Address,
Doc_No,
Issue_Date,
Payment_Term,
Due_Date,
Discount,
Shipping,
SubTotal,
total



please suggest me something. i should change table or give it relation to make it one table.