MySQL selection based on AVG function - mysql

Question

How can I select all Countries which won more than the average number of (any) medal across all countries from the table below:
+-----------+-------------+--------+-----------------+----------------------------+-------------------------------+-----------------------------------------+---------------------------------+-------------------------+
| idRESULTS | STATUS | MEDALS | EVENTS_idEVENTS | EVENTS_ATHLETES_idATHLETES | EVENTS_ATHLETES_TEAMS_idTEAMS | EVENTS_ATHLETES_TEAMS_COUNTRY_idCOUNTRY | EVENTS_VARIOUS_SPORTS_SPORTS_ID | awarded_medals_medal-id |
+-----------+-------------+--------+-----------------+----------------------------+-------------------------------+-----------------------------------------+---------------------------------+-------------------------+
| results1 | DID-NOT-WIN | SILVER | TEN | MS | RUS-WTA | RUS | WOMENS_TENNIS | 2 |
| results1 | WON | GOLD | TEN | VW | USA-WTA | USA | WOMENS_TENNIS | 3 |
| results2 | DID-NOT-WIN | BRONZE | ATH | JG | USA-TF-MEN | USA | TRACK-AND-FIELD | 3 |
| results2 | WON | GOLD | ATH | UB | JAM-TF-MEN | JAM | TRACK-AND-FIELD | 1 |
| results3 | WON | GOLD | TEN-DOUBLE | SW | USA-WTA | USA | WOMENS_TENNIS | 3 |
| results3 | WON | GOLD | TEN-DOUBLE | VW | USA-WTA | USA | WOMENS_TENNIS | 1 |
+-----------+-------------+--------+-----------------+----------------------------+-------------------------------+-----------------------------------------+---------------------------------+-------------------------+
I am using this code :
CREATE VIEW `Countries_Athletes_who_wo_Gold` AS
select * from results where medals = 'Gold'
select EVENTS_ATHLETES_TEAMS_COUNTRY_idCOUNTRY, medals from countries_athletes_who_wo_gold
where medals > (select AVG(medals) from countries_athletes_who_wo_gold) ;
but am not getting the required output?

Answer 1

You first need to write a query that counts the medals for each country.
SELECT EVENTS_ATHLETES_TEAMS_COUNTRY_idCOUNTRY, COUNT(*) AS medal_count
FROM Countries_Athletes_who_wo_Gold
GROUP BY EVENTS_ATHLETES_TEAMS_COUNTRY_idCOUNTRY
Then use this as a subquery twice in your query: once to get each country's medal count, and then to get the average across all countries.
SELECT *
FROM (
SELECT EVENTS_ATHLETES_TEAMS_COUNTRY_idCOUNTRY, COUNT(*) AS medal_count
FROM Countries_Athletes_who_wo_Gold
GROUP BY EVENTS_ATHLETES_TEAMS_COUNTRY_idCOUNTRY
) AS by_country
JOIN (SELECT AVG(medal_count) AS avg_medals
FROM (SELECT EVENTS_ATHLETES_TEAMS_COUNTRY_idCOUNTRY, COUNT(*) AS medal_count
FROM Countries_Athletes_who_wo_Gold
GROUP BY EVENTS_ATHLETES_TEAMS_COUNTRY_idCOUNTRY) AS by_country
) AS all_countries
WHERE medal_count > avg_medals
DEMO