Sql 筛选并比较数组_agg值

我有下一个问题：

SELECT
     type,
     array_agg(DISTINCT food_name) as food,
     portion
FROM stored_meal
WHERE id = 23
AND event_timestamp >= '2020-09-01 19:49:38.634483'
AND event_timestamp < '2020-09-07 19:49:38.634483'

我需要筛选出具有相同“食物项”和“最低部分”的行 预期结果应为：

type       food                portion
launch     {cola, wine, pizza} 4
breakfast  {burger, pepsi}     5

---

我是SQL新手，有什么办法吗？

您可以使用窗口函数：

SELECT type, food, portion
FROM (SELECT type, array_agg(DISTINCT food_name) as food, portion,
             ROW_NUMBER() OVER (PARTITION BY array_agg(DISTINCT food_name) ORDER BY portion DESC) as seqnum
      FROM stored_meal
      WHERE id = 23 AND
           event_timestamp >= '2020-09-01 19:49:38.634483' AND
           event_timestamp < '2020-09-07 19:49:38.634483'
     ) sm
WHERE seqnum = 1;

---

查询没有使用GROUP BY，因此应该失败。这是您的实际代码吗？

SELECT type, food, portion
FROM (SELECT type, array_agg(DISTINCT food_name) as food, portion,
             ROW_NUMBER() OVER (PARTITION BY array_agg(DISTINCT food_name) ORDER BY portion DESC) as seqnum
      FROM stored_meal
      WHERE id = 23 AND
           event_timestamp >= '2020-09-01 19:49:38.634483' AND
           event_timestamp < '2020-09-07 19:49:38.634483'
     ) sm
WHERE seqnum = 1;