我怎样才能计算出的数量

Question

在我们的 Postgres 数据库中，我们想计算自开始以来每天的预订数量。

现在我们有以下查询：

SELECT 
   to_char("domain".bookings.created_at,'dy') AS "Name of the day",
   COUNT ("domain".bookings."id") AS "Number of bookings"
FROM
   "domain".bookings
GROUP BY
   to_char("domain".bookings.created_at,'dy'), 
   "domain".bookings."id"
ORDER BY
   "domain".bookings."id"

不幸的是，它返回以下结果：

tue 1
wed 1
wed 1
sun 1
sat 1
thu 1
wed 1
tue 1

而不是每天的总数。

有没有办法改变公式？

谢谢！

卢卡

Answer 1

导致您出现问题的是 group by。您不想按聚合字段分组

SELECT 
   to_char("domain".bookings.created_at,'dy') AS "Name of the day",
   COUNT ("domain".bookings."id") AS "Number of bookings"
FROM
   "domain".bookings
GROUP BY
   to_char("domain".bookings.created_at,'dy')
ORDER BY
   to_char("domain".bookings.created_at,'dy')

Answer 2

您的分组似乎有误。尝试：

SELECT 
   to_char("domain".bookings.created_at,'dy') AS "Name of the day",
   COUNT ("domain".bookings."id") AS "Number of bookings"
FROM
   "domain".bookings
GROUP BY
   to_char("domain".bookings.created_at,'dy')
ORDER BY
   "Number of bookings"

我怎样才能计算出的数量

How can I count the number of

sql

postgresql

postgresql-9.3