Hello! I am working on a Web application where a user can buy and Sell stocks [closed]

I am working on web app and this my table of stocks I own

symbol     user_id    price   shares         stock
AAPL             1     $10      50         APPLE INC.
TSLA             1     $15      50         TESLA

I am having trouble on selling shares I want to sell 1 share of apple so shares become 49 SO in sql can i do something like sell 1 share of apple whoser user_id = 1 I am using this

db.execute(DELETE share FROM table WHERE user_id = 1 and symbol = aapl)

but its not working