UNION ALL / UNION on Presto
UNION ALL / UNION on Presto
我正在使用 treasure data 进行数据分析,但在 presto db 中使用 union 语句时遇到问题。
如何在 presto 上做一个 Union All。我不明白文档。每次我尝试像这样执行 UNION 时:
SELECT
COUNT(*) AS ReservationsCreated,
resource
FROM
reservation
WHERE
type = 'create'
UNION
SELECT
COUNT(*) AS ReservationsDeleted,
resource
FROM
reservation
WHERE
type = 'delete'
GROUP BY
resource
;
我将输出重新格式化为:
SELECT
COUNT(*) AS ReservationsCreated,
resource
FROM
reservation
WHERE
type = 'create'
UNION
SELECT
COUNT(*) AS ReservationsDeleted,
resource
FROM
reservation
WHERE
type = 'delete'
GROUP BY
resource
;
错误提示:
'"resource"' must be an aggregate expression or appear in GROUP BY clause
我想我不理解 Presto 的语法。 Union 上的文档非常混乱。任何帮助表示赞赏。
如错误所述,查询的第一部分缺少 group by
。
SELECT COUNT(*) AS ReservationsCreated, resource
FROM reservation
WHERE type = 'create'
group by resource
UNION ALL
SELECT COUNT(*) AS ReservationsDeleted, resource
FROM reservation
WHERE type = 'delete'
GROUP BY resource
事实上,查询可以简化为使用条件聚合。
select
resource
,sum(case when type = 'create' then 1 else 0 end) as reservationscreated
,sum(case when type = 'delete' then 1 else 0 end) as reservationsdeleted
from reservation
group by resource
我正在使用 treasure data 进行数据分析,但在 presto db 中使用 union 语句时遇到问题。
如何在 presto 上做一个 Union All。我不明白文档。每次我尝试像这样执行 UNION 时:
SELECT
COUNT(*) AS ReservationsCreated,
resource
FROM
reservation
WHERE
type = 'create'
UNION
SELECT
COUNT(*) AS ReservationsDeleted,
resource
FROM
reservation
WHERE
type = 'delete'
GROUP BY
resource
;
我将输出重新格式化为:
SELECT
COUNT(*) AS ReservationsCreated,
resource
FROM
reservation
WHERE
type = 'create'
UNION
SELECT
COUNT(*) AS ReservationsDeleted,
resource
FROM
reservation
WHERE
type = 'delete'
GROUP BY
resource
;
错误提示:
'"resource"' must be an aggregate expression or appear in GROUP BY clause
我想我不理解 Presto 的语法。 Union 上的文档非常混乱。任何帮助表示赞赏。
如错误所述,查询的第一部分缺少 group by
。
SELECT COUNT(*) AS ReservationsCreated, resource
FROM reservation
WHERE type = 'create'
group by resource
UNION ALL
SELECT COUNT(*) AS ReservationsDeleted, resource
FROM reservation
WHERE type = 'delete'
GROUP BY resource
事实上,查询可以简化为使用条件聚合。
select
resource
,sum(case when type = 'create' then 1 else 0 end) as reservationscreated
,sum(case when type = 'delete' then 1 else 0 end) as reservationsdeleted
from reservation
group by resource