尝试根据值删除 sqlite 中的行时出现内部服务器错误

Question

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I am trying to create an app for buying and selling stocks. If I sell all stocks from the same company, I want to delete the row instead of displaying 0 shares. I am not sure how to delete the row based on its value.

It gives me error incomplete input here:

db.execute("INSERT INTO stocks (user_id, symbol, name, shares, price, total_cost, transaction_type) VALUES(:user_id, :symbol, :name, :shares, :price, :total_cost, :transaction_type", user_id=user_id, name=name, symbol=symbol, shares= -1*shares, price=price, total_cost=total_cost, transaction_type=transaction_type)

This line of code was working before I added the delete condition.

@app.route("/sell", methods=["GET", "POST"])
@login_required
def sell():

    """Sell shares of stock"""
    #Access the current user
    user_id= session["user_id"]

    if request.method =="POST":
        if not request.form.get("symbol") or not request.form.get("shares"):
            return apology("Enter a valid symbol or number of shares")

        #Define data
        symbol=request.form.get("symbol")
        shares=int(request.form.get("shares"))
        stock=lookup(symbol)
        price=stock.get("price")
        total_cost=int(shares)*stock["price"]
        name=stock.get("name")
        transaction_type="sale"

        if stock is None:
            return apology("Enter a valid symbol")

        #Access existing data in DB

        rows= db.execute("SELECT symbol, sum(shares) as shares FROM stocks WHERE user_id=:user_id GROUP BY symbol", user_id=user_id)


        #Validate if the current user owns the shares they are trying to sell
        for row in rows:
            if row["symbol"]==symbol:
                if shares > row["shares"]:
                    return apology("Enter a valid number of shares")
                if row["shares"]-shares==0:
                    db.execute("DELETE FROM stocks WHERE user_id = :user_id AND symbol = :symbol",
                          symbol=symbol, user_id=session["user_id"])


        user=db.execute("SELECT cash FROM users WHERE id=:user_id", user_id=user_id)
        new_cash=user[0]["cash"]+total_cost
        #Add transaction to the db
        #Update DB cash of the user

        db.execute ("UPDATE users SET cash=:new_cash WHERE id=:id", new_cash=new_cash, id=user_id)
        db.execute("INSERT INTO stocks (user_id, symbol, name, shares, price, total_cost, transaction_type) VALUES(:user_id, :symbol, :name, :shares, :price, :total_cost, :transaction_type", user_id=user_id, name=name, symbol=symbol, shares= -1*shares, price=price, total_cost=total_cost, transaction_type=transaction_type)

        return redirect("/")

    else:
        share_symbols=[]
        symbs = db.execute("SELECT symbol FROM stocks WHERE user_id=:user_id GROUP BY symbol",
        user_id=user_id)
        for symb in symbs:
            share_symbols.append(symb)
        return render_template("sell.html", share_symbols=share_symbols)

Answer 1

One problem is order of execution. This

db.execute("DELETE FROM stocks WHERE user_id = :user_id AND symbol = :symbol",
                          symbol=symbol, user_id=session["user_id"])

deletes all stocks rows if shares will become 0.

Subsequently,

db.execute("INSERT INTO stocks (user_id, symbol, name, shares, price, total_cost, transaction_type) VALUES(:user_id, :symbol, :name, :shares, :price, :total_cost, :transaction_type", user_id=user_id, name=name, symbol=symbol, shares= -1*shares, price=price, total_cost=total_cost, transaction_type=transaction_type)

inserts a row with negative shares.

It looks like the stocks table keeps one row per transaction, not one row per stock. Which would be useful for the history route. Don't delete any rows.

One solution would be a modification, probably in index. Assuming a SELECT with sum(shares), add a HAVING clause to filter out rows where sum(shares) is 0.