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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我正在尝试创建一个用于买卖股票的应用程序。如果我出售同一家公司的所有股票，我想删除该行而不是显示 0 股。 我不确定如何根据其值删除该行。

这里给了我错误不完整的输入：

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)

这行代码在我添加删除条件之前就可以工作了。

@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

一个问题是执行顺序。这个

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

如果股票将变为0，则删除所有股票行。

随后，

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)

插入负份额的行。

看起来，stocks 表每笔交易保留一行，而不是每只股票保留一行。这对历史路线很有用。不要删除任何行。

一个解决方案是修改，可能在 index.html 中。假设一个带有 sum(shares) 的 SELECT，添加 a HAVING clause 以过滤掉 sum(shares) 为 0 的行。