按错误分组：PG :: GroupingError：ERROR：列必须出现在GROUP BY子句中或用于聚合函数

Question

我有一个列utc_time，其中存储了unix时间戳，

我希望按日期分组，

但是有错误。

  def self.memory_info_daily(test_id=1)
    self.unscoped
    .where{ name =~ 'MemoryInfo' }
    .where{ sony_alarm_test_id.eq(test_id)}
    .group("to_char(to_timestamp(utc_time), 'YYYY-MM-DD')")

但它的工作原理是在查询结尾附加.count。

错误

SELECT "sony_alarm_logs".* FROM "sony_alarm_logs" WHERE "sony_alarm_logs"."name" ILIKE 'MemoryInfo' AND "sony_alarm_logs"."sony_alarm_test_id" = 1 GROUP BY to_char(to_timestamp(utc_time), 'YYYY-MM-DD')
E, [2014-06-27T16:17:14.379965 #29797] ERROR -- : PG::GroupingError: ERROR:  column "sony_alarm_logs.id" must appear in the GROUP BY clause or be used in an aggregate function
LINE 1: SELECT "sony_alarm_logs".* FROM "sony_alarm_logs"  WHERE "so...
               ^