php mysql表2的数量和表1的字段组合

Question

i want to sum amount from sale table and want to group it by brand, can anyone help me to right query of php mysql.

--- product ---

id  pcode   pname   brand
1   123     Dalda   1
2   124     Habib   1
3   125     Sufi    2
4   126     Toyota  3



--- sale ---
id  pcode   pname   amount
1   123     Dalda   1020
2   123     Dalda   1020
3   124     Habib   1030
4   124     Habib   1030
5   125     Sufi    1040
6   125     Sufi    1040
7   126     Toyota  1050

Answer 1

SELECT
  p.pname,
  IFNULL(SUM(amount), 0) AS TotalAmount
FROM product p
LEFT JOIN sale s ON p.pcode = s.pcode
GROUP BY p.pname;

SQL Fiddle Demo

This will give you:

|  PNAME | TOTALAMOUNT |
------------------------
|  Dalda |        2040 |
|  Habib |        2060 |
|   Sufi |        2080 |
| Toyota |        1050 |

Note that: There is no need to store the pname in the second table Sale . Remove it since it is already stored in the first table Product .

Answer 2

select p.brand, sum(s.amount)
FROM product p
INNER JOIN sale s on s.pcode = p.pcode
GROUP BY p.brand 

You will get only brands with an entry in sales table.

if you want all the brands, even without an entry in sale table, then use a LEFT JOIN and

COALESCE(SUM(amount, 0))

By the way, as pointed by Mahmoud Gamal, you don't need the pname in table Sale. I wouldn't use pcode as "relation column" also, but use product id. So you may remove pcode and pname and use a new column p_id, for example.

Answer 3

select pr.pcode,pr.pname,pr.brand,sum(s.amount)
from product pr
left join sale s
on pr.pcode=s.pcode
group by pr.pcode,pr.pname,pr.brand