Question

我遇到此查询的问题。我想选择ID字段，然后日期时间戳字段具有别名，但别名具有组别。如果没有包含ID字段，我就无法做到，但之后它不会保持group by提供的唯一性。这是我的查询不起作用。我收到有关需要包含ID字段的错误。

SELECT id, to_timestamp(start_date)::date as sdate FROM events WHERE end_date > 1349306845 GROUP BY sdate ORDER BY sdate ASC LIMIT 20

更新：使用下面的功能后，它可以根据需要工作。

   SELECT max(id) as id, to_timestamp(start_date)::date as sdate FROM events WHERE end_date > 1349306845 GROUP BY sdate ORDER BY sdate ASC LIMIT 20

Answer 1

SELECT  id, to_timestamp(start_date)::date as sdate 
FROM events
WHERE start_date IN 
   (
     SELECT start_date as sdat 
     FROM events 
     WHERE end_date > 1349306845 
     GROUP BY sdat 
     ORDER BY sdat 
     ASC LIMIT 20 
   )

SELECT  id, to_timestamp(start_date)::date as sdate 
FROM events
WHERE start_date IN 
   (
     SELECT start_date as sdat 
     FROM events 
     WHERE end_date > 1349306845 
     GROUP BY sdat 
   )
ORDER BY sdate 
ASC LIMIT 20

在Postgresql中选择带别名的多列和按别名分组

1 个答案: