Update table based on result of select on another table - mysql

Question

I have two tables like this:
person:
id | name | sale | commission
1 | abc | 0 | 0
2 | xyz | 0 | 0
sale:
id | date | person_id | sale | commission
1 | 2016-05-01 | 1 | 10 | 1
2 | 2016-05-02 | 1 | 10 | 1
3 | 2016-05-03 | 1 | 10 | 1
4 | 2016-05-01 | 2 | 20 | 2
5 | 2016-05-02 | 2 | 20 | 2
6 | 2016-05-01 | 2 | 20 | 2
I want to update person table with single update query and change the table something like this:
person:
id | name | sale | commission
1 | abc | 30 | 3
2 | xyz | 60 | 6
I know I can sum sale like following but how to update following query result into person table directly.
SELECT person_id, SUM(sale), SUM(commission)
FROM sale
GROUP BY person_id;

Answer 1

As Strawberry said in the comments under your question, think long and hard before you save this information. It is denormalized, and it becomes stale. Rather, consider using it during report generation. Otherwise, well, as said, you may run into problems.
drop table if exists person;
create table person
( personId int auto_increment primary key,
name varchar(100) not null,
totSales decimal(9,2) not null,
totComm decimal(9,2)
);
insert person(name,totSales,totComm) values
('Joe',0,0),
('Sally',0,0);
-- just added persons 1 and 2 (auto_inc)
drop table if exists sale;
create table sale
( saleId int auto_increment primary key,
saleDate date not null,
personId int not null,
sale decimal(9,2) not null,
commission decimal(9,2) not null,
index(personId), -- facilitate a snappier "group by" later
foreign key (personId) references person(personId) -- Ref Integrity
);
insert sale(saleDate,personId,sale,commission) values
('2016-05-01',2,10,1),
('2016-05-01',1,40,4),
('2016-05-02',1,30,3),
('2016-05-07',2,10,1),
('2016-05-07',2,90,9);
-- the following dies on referential integrity, FK, error 1452 as expected
insert sale(saleDate,personId,sale,commission) values ('2016-05-01',4,10,1);
The update statement
update person p
join
( select personId,sum(sale) totSales, sum(commission) totComm
from sale
group by personId
) xDerived
on xDerived.personId=p.personId
set p.totSales=xDerived.totSales,p.totComm=xDerived.totComm;
The results
select * from person;
+----------+-------+----------+---------+
| personId | name | totSales | totComm |
+----------+-------+----------+---------+
| 1 | Joe | 70.00 | 7.00 |
| 2 | Sally | 110.00 | 11.00 |
+----------+-------+----------+---------+
2 rows in set (0.00 sec)
xDerived is merely an alias name. All derived tables need an alias name, whether or not you use the alias name explicitly.

Answer 2

UPDATE person
SET sale = (
SELECT SUM(s.sale) FROM sale s
WHERE s.person_id = person.id
);
works for me. See it in action at: http://ideone.com/F32oUU
EDIT for new version with additional aggregated column:
UPDATE person SET
sale = (
SELECT SUM(s.sale) FROM sale s
WHERE s.person_id = person.id
),
commission = (
SELECT SUM(s.commission) FROM sale s
WHERE s.person_id = person.id
);
http://ideone.com/yo1A9Y
This being said, I feel sure that a JOIN solution is better, and am hopeful another answerer will be able to post such a solution.