##TO DO
- Modify transaction ids case. \ will leave cause no full integration
- db.new_stockist_form me primary(name,phone,address,date)
- drop db.purchase and add cust_id to db.invoice <>
- stock purchase calculate gross total etc total tax amt
- At end create trigger before update and delete on "invoice,order_item,purchase,stock"
- Admin is given privilages which is not available to customers or staffs(except owner).
- Admin can generate electronic invoice online on this site.
- Public login url is not published on the site, because of security.
- Invoice page-> you can't buy more items than available.
- Password is appended with salt and its sha256 hash is stored in password. Can't be reversed.
- Trigger is created on medicine_available so that available_quantity can't be negative.