Question

I have 2 tables HOUSES and COUNTRIES

HOUSES

country_code – example ‘ES’ for Spain

COUNTRIES

country_code – example ‘ES’ for Spain

houses_total – example 20 – total houses in ‘ES’ Spain found in the HOUSES table

I need to count the number of houses in each HOUSES.country_code in the HOUSES table and update the COUNTRIES table with that total in COUNTRIES.houses_total

Many thanks

Answer 1

Use join with update:

Try below:

Update countries as c 
left join  (SELECT COUNT(*) as totalcount,country_code  
            FROM HOUSES 
            GROUP BY country_code) as tc 
on c.country_code =tc.country_code  
set c.houses_total =tc.totalcount