mysql对每一行求和

Question

query to get the results as below

table price( item int, amount int, quantity int, )

+-------+-------+----------+
| item  | price | quantity |
+-------+-------+----------+
| box 1 |  1000 |        4 |
| box 2 |  2000 |        1 |
| box 3 |  3000 |        6 |
+-------+-------+----------+

---

result

+-------+-------+----------+-----------+-------+
| item  | price | quantity | sub total | total |
+-------+-------+----------+-----------+-------+
| box 1 |  1000 |        4 |      4000 | 16000 |
| box 2 |  2000 |        1 |      2000 | 18000 |
| box 3 |  3000 |        6 |     18000 | 36000 |
+-------+-------+----------+-----------+-------+

Answer 1

You can try below if your mysql version below 8.0

select 
    item,price,quantity,price*quantity as total, 
    @totalall:= @totalall + price*quantity as TotalAll
from price, (Select @totalall:= 0) as totalall;

OR if your mysql vsersion 8.0+ then you can try below -

SELECT 
    item,price,quantity,price*quantity as total, 
    SUM(price*quantity) OVER(ORDER BY item) AS TotalAll
FROM price;

Answer 2

从交叉联接中选择数量，（@ sum：= @ sum +（item * amount））作为数量（选择@sum：= 0）参数