Re: query based on row number for psql8.3

From: Stephen Tahmosh <stahmosh(at)shieldsrx(dot)com>
To: Stephen Tahmosh <stahmosh(at)shieldsrx(dot)com>, "emilu(at)encs(dot)concordia(dot)ca" <emilu(at)encs(dot)concordia(dot)ca>, "pgsql-sql(at)postgresql(dot)org" <pgsql-sql(at)postgresql(dot)org>
Subject: Re: query based on row number for psql8.3
Date: 2016-03-23 18:13:15
Message-ID: DM2PR0701MB1295F2FFD6EF372E3D89FE63C4810@DM2PR0701MB1295.namprd07.prod.outlook.com
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A "goggle" of row_number() function for postgresql seems to indicate its only available in 8.4 and above :-(

-----Original Message-----
From: pgsql-sql-owner(at)postgresql(dot)org [mailto:pgsql-sql-owner(at)postgresql(dot)org] On Behalf Of Stephen Tahmosh
Sent: Wednesday, March 23, 2016 2:10 PM
To: emilu(at)encs(dot)concordia(dot)ca; pgsql-sql(at)postgresql(dot)org
Subject: Re: [SQL] query based on row number for psql8.3

Row_number is an "analytic" function, used in conjunction with the "partition by"
Ror_number is a logical concept so depends on the "order by" component of the "partition by" clause

You need to wrap your query with row_number in an outer query and apply thye case statement to the outer query.

-----Original Message-----
From: pgsql-sql-owner(at)postgresql(dot)org [mailto:pgsql-sql-owner(at)postgresql(dot)org] On Behalf Of Emi
Sent: Wednesday, March 23, 2016 2:01 PM
To: pgsql-sql(at)postgresql(dot)org
Subject: [SQL] query based on row number for psql8.3

Hello,

For psql8.3, is there a simple way to query based on row number please?

For example,

select case
when row_num=1 THEN t1.tot_hr
ELSE t1.tot_hr -
t1.pre_hr
END
FROM t1 ;

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