Postgres 12

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CREATE TABLE countries (
  	continent text NOT NULL,
    country text NOT NULL,
    date date NOT NULL,
    value integer,
    id SERIAL UNIQUE PRIMARY KEY
);

CREATE UNIQUE INDEX countries_pk ON countries(id int4_ops);

INSERT INTO "countries"("continent","country","date","value","id")
VALUES
(E'Europe',E'Germany',E'2020-05-25',10,1),
(E'Europe',E'Germany',E'2020-05-26',11,2),
(E'Europe',E'Germany',E'2020-05-27',12,3),
(E'Europe',E'Germany',E'2020-05-28',13,4),
(E'Europe',E'Italy',E'2020-05-25',20,5),
(E'Europe',E'Italy',E'2020-05-26',21,6),
(E'Europe',E'Italy',E'2020-05-27',22,7),
(E'Europe',E'Italy',E'2020-05-28',23,8),
(E'Europe',E'France',E'2020-05-25',30,9),
(E'Europe',E'France',E'2020-05-26',31,10),
(E'Europe',E'France',E'2020-05-27',32,11),
(E'Europe',E'France',E'2020-05-28',NULL,12),
(E'Africa',E'Congo',E'2020-05-25',40,13),
(E'Africa',E'Congo',E'2020-05-26',41,14),
(E'Africa',E'Congo',E'2020-05-27',NULL,15);
15 rows affected

SELECT c.continent, c.date,
       SUM(c.value) AS value,
        COUNT(c.country) AS countries_count
FROM (SELECT c.*,
             COUNT(*) OVER (PARTITION BY continent, date) as num_on_date
      FROM countries c
      WHERE value IS NOT NULL
     ) c JOIN
     (SELECT continent, COUNT(DISTINCT country) as num_countries
      FROM countries
      GROUP BY continent
     ) cc
     ON cc.continent = c.continent
WHERE num_on_date = num_countries
GROUP BY c.continent, c.date
ORDER BY c.date DESC, c.continent;


continent
date
value
countries_count


Europe
2020-05-27
66
3

Africa
2020-05-26
41
1

Europe
2020-05-26
63
3

Africa
2020-05-25
40
1

Europe
2020-05-25
60
3


SELECT c.continent, c.date,
       SUM(c.value) AS value,
        COUNT(c.country) AS countries_count
FROM countries c
WHERE value IS NOT NULL
GROUP BY c.continent, c.date
HAVING COUNT(*) = (SELECT COUNT(DISTINCT c2.country)
                   FROM countries c2
                   WHERE c2.continent = c.continent
                  )
ORDER BY c.date DESC, c.continent;


continent
date
value
countries_count


Europe
2020-05-27
66
3

Africa
2020-05-26
41
1

Europe
2020-05-26
63
3

Africa
2020-05-25
40
1

Europe
2020-05-25
60
3
continent	date	value	countries_count
Europe	2020-05-27	66	3
Africa	2020-05-26	41	1
Europe	2020-05-26	63	3
Africa	2020-05-25	40	1
Europe	2020-05-25	60	3