Re: row_number ignores where clause w/ order by

From: Patrick Conner via MIDRANGE-L <midrange-l@xxxxxxxxxxxx>
To: midrange-l@xxxxxxxxxxxx,
Cc: Patrick Conner <pwconner@xxxxxxx>
Date: 11/30/2018 08:17 AM
Subject: Re: row_number ignores where clause w/ order by
Sent by: "MIDRANGE-L" <midrange-l-bounces@xxxxxxxxxxxx>


Jack,


Thanks. Charles provided a similar statement earlier. And I get the
CTE works.

But I'm still curious that the row_number function works differently
based on the 'order by' clause. Charles mentioned earlier that he
suspects the regExp_like is the culprit, but regExp_like is in the
statement that numbers only the resulting records and it is in the
statement that numbers the records before applying the 'where' clause.
If someone can provide an explanation, I'm listening. Otherwise,
I've moved on with the CTE.



Thanks to the mailing list for everyone's help



-----Original Message-----
From: Jack Callahan <jjcllhn@xxxxxxxxx>
To: midrange-l <midrange-l@xxxxxxxxxxxx>
Sent: Fri, Nov 30, 2018 8:41 am
Subject: RE: row_number ignores where clause w/ order by

I think this works the way you expect (row numbers assigned by

size for the selected tables:

With SelectTables AS
(select *
from qSys2.sysTableStat
where regExp_like( table_schema, 'JJCWORK' )
order by data_size desc
)
SELECT row_number() over(order by data_size desc) as rowNumber,s.* from
SelectTables s;