Question

: SELECT created_at, count(created_at) as count FROM "candidates"  GROUP BY date(created_at)
ActiveRecord::StatementInvalid: PG::GroupingError: ERROR:  column "candidates.created_at" must appear in the GROUP BY clause or be used in an aggregate function

created_at是日期时间列

candidates是一个表格

如何让它发挥作用？感谢。

Answer 1

问题是您正在选择created_at作为单独的列。您需要在其周围使用聚合函数（如MIN或MAX）或将其添加到GROUP BY。

由于您已经按date(created_at)进行分组，因此您可能希望在选择中使用该分组。所以像这样：

SELECT
    DATE(created_at),
    COUNT(created_at) as count
FROM "candidates"
GROUP BY date(created_at)

这个Postgres查询有什么问题？

1 个答案: