ERROR:  column "XYZ" must appear in the GROUP BY clause or be used in an aggregate function

有人可以告诉我我做错了什么？

MysqL工作100％：

SELECT `availables`.* FROM `availables` INNER JOIN `rooms` ON `rooms`.id = `availables`.room_id WHERE (rooms.hotel_id = 5056 AND availables.bookdate BETWEEN '2009-11-22' AND '2009-11-24') GROUP BY availables.bookdate ORDER BY availables.updated_at

Postgresql错误：

ActiveRecord::StatementInvalid: PGError: ERROR:  column "availables.id" must appear in the GROUP BY clause or be used in an aggregate function
: SELECT "availables".* FROM "availables"   INNER JOIN "rooms" ON "rooms".id = "availables".room_id  WHERE (rooms.hotel_id = 5056 AND availables.bookdate BETWEEN E'2009-10-21' AND E'2009-10-23')  GROUP BY availables.bookdate ORDER BY availables.updated_at

Ruby代码生成sql：

expiration = Available.find(:all,:joins => [ :room ],:conditions => [ "rooms.hotel_id = ? AND availables.bookdate BETWEEN ? AND ?",hostel_id,date.to_s,(date+days-1).to_s ],:group => 'availables.bookdate',:order => 'availables.updated_at')

预期输出(从工作mySQL查询)：

+-----+-------+-------+------------+---------+---------------+---------------+
| id  | price | spots | bookdate   | room_id | created_at    | updated_at    |
+-----+-------+-------+------------+---------+---------------+---------------+
| 414 | 38.0  | 1     | 2009-11-22 | 1762    | 2009-11-20... | 2009-11-20... |
| 415 | 38.0  | 1     | 2009-11-23 | 1762    | 2009-11-20... | 2009-11-20... |
| 416 | 38.0  | 2     | 2009-11-24 | 1762    | 2009-11-20... | 2009-11-20... |
+-----+-------+-------+------------+---------+---------------+---------------+
3 rows in set