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@postgresql.org [mailto:pgsql-sql-owner@postgresql.org] On Behalf Of Emi
Sent: Wednesday, March 23, 2016 2:01 PM
To: pgsql-sql@postgresql.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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