Re: [SQL] HAVING confusion..

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От Oliver Elphick
Тема Re: [SQL] HAVING confusion..
Дата
Msg-id 199902220707.HAA20343@linda.lfix.co.uk
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Ответ на HAVING confusion..  ("George Henry C. Daswani" <gdaswani@Vorlon.odc.net>)
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"George Henry C. Daswani" wrote:
  >Hello,
  >
  >    I'm using postgresql 6.4.2 and i'm having a problem with the
  >"HAVING" clause..
  >
  >
  >Basically I do
  >
  >SELECT u_id,expire_date FROM users HAVING expire_date >= (NOW())
...
  >and it keeps failing with
  >ERROR:  This is not a valid having query!

You should only use HAVING with GROUP BY; for what you are doing, you
just want WHERE.

SELECT u_id,expire_date FROM users
   WHERE expire_date >= date(now());
u_id |expire_date
-----+-----------
fred | 21-03-1999
tom  | 01-05-1999
harry| 01-05-1999
sarah| 21-03-1999
dick | 12-04-1999
(5 rows)

SELECT expire_date,COUNT(*) FROM users
   GROUP BY expire_date
   HAVING expire_date >= date(now());
expire_date|count
-----------+-----
 21-03-1999|    2
 12-04-1999|    1
 01-05-1999|    2
(3 rows)

--
Oliver Elphick                                Oliver.Elphick@lfix.co.uk
Isle of Wight                              http://www.lfix.co.uk/oliver
               PGP key from public servers; key ID 32B8FAA1
                 ========================================
     "The LORD bless thee, and keep thee; The LORD make his
      face shine upon thee, and be gracious unto thee; The
      LORD lift up his countenance upon thee, and give thee
      peace."              Numbers 6:24-26



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