如何计算foreach语句的所有结果

Question

Let say we have following database table items

-----------------------------
ID |  ITEM  | PRICE | SALES |
-----------------------------
1  | item1  | 5.00  | 1     |
2  | item2  | 4.00  | 5     |
3  | item3  | 2.00  | 2     |
-----------------------------

This means item1 price was 5.00 and sold 1 times

how then we calculate total earning ! meaning for each item we will multpli its price with number of sale to get total earning for this item

$earning_per_item1 = $a1['PRICE']*$a1['SALES']; // for item1 = 5*1

But what if i want to get the total earning for all items?

This should be 29

Answer 1

Try something like that:

SELECT sum(i.PRICE * i.SALES)
FROM items i;

SQLFIDDLE