Gold Medals by Demographic Group
(Western European Countries Only)
+----------+--------------------+-------+
| season | demographic_group | golds |
|----------+--------------------+-------|
| Winter | Male Age 26+ | 13 |
| Winter | Female Age 26+ | 8 |
| Summer | Male Age 13-25 | 7 |
| Summer | Female Age 13-25 | 6 |
| Winter | Male Age 13-25 | 4 |
| Summer | Male Age 26+ | 4 |
| Winter | Female Age 13-25 | 4 |
| Summer | Female Age 26+ | 2 |
+----------+--------------------+-------+
関連テーブル
関連テーブル
オプションA: 先にJOIN、次にUNION
オプションA: 先にJOIN、次にUNION
手順 1: 上側のJOIN付きクエリを作成
SELECT
athlete_id,
gender,
age,
gold
FROM summer_games AS sg
JOIN athletes AS a
ON sg.athlete_id = a.id;
Query ran successfully!
オプションA: 先にJOIN、次にUNION
手順 2: 下側のクエリを作成し、2つをUNIONで結合
SELECT
athlete_id,
gender,
age,
gold
FROM summer_games AS sg
JOIN athletes AS a
ON sg.athlete_id = a.id
UNION ALL
SELECT
athlete_id,
gender,
age,
gold
FROM winter_games AS wg
JOIN athletes AS a
ON wg.athlete_id = a.id;
オプションB: 先にUNION、次にJOIN
オプションB: 先にUNION、次にJOIN
手順 1: 最初のUNIONを作成
SELECT
athlete_id,
gold
FROM summer_games AS sg
UNION
SELECT
athlete_id,
gold
FROM winter_games AS wg;
オプションB: 先にUNION、次にJOIN
手順 2: サブクエリにしてJOIN
SELECT
athlete_id,
gender,
age,
gold
FROM
(SELECT
athlete_id,
gold
FROM summer_games AS sg
UNION ALL
SELECT athlete_id, gold
FROM winter_games AS wg) AS g
JOIN athletes AS a
ON g.athlete_id = a.id;
比較
オプションA
SELECT
athlete_id,
gender,
age,
gold
FROM summer_games AS sg
JOIN athletes AS a
ON sg.athlete_id = a.id
UNION ALL
SELECT
athlete_id,
gender,
age,
gold
FROM winter_games AS wg
JOIN athletes AS a
ON wg.athlete_id = a.id;
オプションB
SELECT
athlete_id,
gender,
age,
gold
FROM
(SELECT
athlete_id,
gold
FROM summer_games AS sg
UNION ALL
SELECT athlete_id, gold
FROM winter_games AS wg) AS g
JOIN athletes AS a
ON g.athlete_id = a.id;
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