試用のために、国とサイトごとに 2 つの日付間の日数の最小/最大/平均を選択する正しい SQL クエリを作成するのに問題があります。
私のクエリ:
SELECT v.country as country, v.site as site,
COUNT(*) as N --,
--MAX(list of durations in days between discovered date to repored date on each violation by country and site) as "Maximum",
--MIN(list of durations in days between discovered date to repored date on each violation by country and site) as "Minimum",
--AVG(list of durations in days between discovered date to repored date on each violation by country and site) as "Mean"
FROM violations v
WHERE v.trial_id = 3
GROUP BY ROLLUP (v.country, v.site)
これは、コメント行を改善するために必要なデータ構造とクエリを備えた私のSQLFIDDLEです。
私を手伝ってくれますか?