How to build sql query?

Question

MySQL

There is a sites table with id and name fields and a reviews table with value and id_site fields
For one value from the sites table there can be several values ​​from the reviews table, you must not just link these two tables, but sum all the values ​​from the reviews table for the corresponding value from the sites
table For example:
sites
id - name
-----------
1 - site.ru
2 - site.com
-----------------
reviews
id_site - value
-- ---------------
1 - 3
1 - 4
The result should be:
1 - site.ru - 7
2 - site.com - null
How to get such a result with one sql query?

Answer 1

SELECT s.name, sum(r.value) FROM reviews as r
LEFT JOIN sites as s ON s.id = r.site_id
GROUP BY r.id_site