[Solved] SQL request with JOIN and COUNT

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If I am reading your question right, the result table give you the age ID and Period, and then the count of toys per age ID and Period. Here is how you would write that query:

SELECT Ages.ID, Ages.Period, IFNULL(sub.cnt,0) AS Count
FROM Ages LEFT JOIN
(SELECT Toys.age_id, COUNT(*) AS cnt
FROM Toys
GROUP BY Toys.age_id) sub
ON Ages.ID = sub.age_id

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solved SQL request with JOIN and COUNT