SELECT
COALESCE(r.name, '''') AS name,
d.year_start AS year,
SUM(d.value * d_nom.value) / SUM(d_nom.value) AS value
FROM
pop_total_access_water AS d
RIGHT JOIN
countries_view AS c ON c.id = d.id_country
RIGHT JOIN
pop_total AS d_nom ON d_nom.id_country = d.id_country
RIGHT JOIN
subregions_view AS r ON r.id = c.sreg_id
WHERE
(d.year_start = 1990 ) AND
(d_nom.year_start = 1990 ) AND
d_nom.value <> 0
GROUP BY
r.name, d.year_start
ORDER BY 1,2
Now, I would like to use from table "d_nom" only these countries
which have a value in table "d" as well.
Without thinking much (so this may be completely wrong for some reason/additional
changes may be needed), why do you use a right join to the d_nom table?
An ordinary inner join should give you only these countries which have
their rows in the d table.
Thanks for that. Ok, tried that, didn't work. But gave me the go into the right direction. Stripped down the query to the absolute necessary, on a country basis, and realized that I have in some tables NULL values. So, the correct SQL is then (with the added line: (d.value IS NOT NULL )):
SELECT COALESCE(r.name, '''') AS name, d.year_start AS year, SUM(d.value * d_nom.value) / SUM(d_nom.value) AS value FROM pop_total_access_water AS d RIGHT JOIN countries_view AS c ON c.id = d.id_country RIGHT JOIN pop_total AS d_nom ON d_nom.id_country = d.id_country RIGHT JOIN subregions_view AS r ON r.id = c.sreg_id WHERE (d.year_start = 1990 ) AND (d.value IS NOT NULL ) AND (d_nom.year_start = 1990 ) AND d_nom.value <> 0 GROUP BY r.name, d.year_start ORDER BY 1,2
Thanks a lot!
Stef