javascript - Questions about calculating the total price of different products

Question

Now there are different products with different calculation formulas, such as product A, the calculation formula is: quantity X duration X unit price. Product B: unit price * quantity.
Please store the calculation formula and match it by yourself.

Answer 1

    $math = '%s*%s';
    $str  = sprintf($math, 5, 6);
    $result=eval("return $str;");
    var_dump($result);

Answer 2

Give each product a flag directly, and then save the company in turn. When matching, you only need to match the flag to find the formula.

Answer 3

Constructor, determines the execution content based on the parameters passed in

Answer 4

select 商品A "商品名", 数量X时长X单价 "总计"
from table
where 商品=商品A
union all
select 商品B "商品名", 数量X单价 "总计"
from table
where 商品=商品B

If it is product A

select 商品B "商品名", 数量X单价 "总计"
from table
where 商品=商品B

No result will be returned