>>Actually I want to use codes to EDIT sale invoice
>>
>>current sale invoice is as follows
>>
>>vou_no--code---Product---qty---rate--Amount
>>---1-------1401----Apple------10----15----150
>>---1-------1402----mango-----20----15----300
>>
>>
>>Now I want to edit current invoice as
>>
>>vou_no--code---Product---qty---rate--Amount
>>---1-------1401----Apple------10----17----170
>>---1-------1403----Banana----30----22----660
>>
>>After editing, I delete current invoice and insert new one on its place with same vou_no.
>
>What is the Primary Key column in the Invoice table? Why do you need to delete and insert instead of simply using UPDATE command?

There is no Primary key becuase this is a products detail table and every product have vou_no reference like this

vou_no--code---Product---qty---rate--Amount
---1-------1401----Apple------10----17----170
---1-------1403----Banana----30----22----660