MAX(rownumber) and count issue

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MAX(rownumber) and count issue

M A Srinivas

SSC-Addicted

Points: 494
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February 10, 2014 at 2:53 am

#282261

declare @a table( keyid int,keyname varchar(50) )
declare @b-2 table( keyid int,keyname varchar(50) )
insert into @a values (1,'10')
insert into @a values (1,'10')
insert into @a values (2,'20')
insert into @a values (4,'40')
insert into @a values (6,'60')
insert into @a values (8,'80')
insert into @a values (9,'90')
insert into @b-2 values (1,'100')
insert into @b-2 values (3,'300')
insert into @b-2 values (5,'500')
insert into @b-2 values (6,'600')
insert into @b-2 values (8,'800')
insert into @b-2 values (8,'801')
-- Below query gives totalrows = 7 , if I remark count
;with rowcte as
(
select a.keyid as akeyid,a.keyname as akeyname , b.keyid as bkeyid ,b.keyname as bkeyname,
row_number() over( order by a.keyid asc ) as rowasc
from @a a
left outer join @b-2 b
on a.keyid = b.keyid
)
select max(rowasc) totoalrows --,count(*) as totcount
from rowcte
-- Below query gives totalrows = 8 and totcount = 8 WHY ?
;with rowcte as
(
select a.keyid as akeyid,a.keyname as akeyname , b.keyid as bkeyid ,b.keyname as bkeyname,
row_number() over( order by a.keyid asc ) as rowasc
from @a a
left outer join @b-2 b
on a.keyid = b.keyid
)
select max(rowasc) totoalrows ,count(*) as totcount
from rowcte

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Abu Dina SSChampion Points: 14155 More actions · Answer 1

The first query gives me 8 and the second gives me 8, 8?!

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M A Srinivas SSC-Addicted Points: 494 More actions · Answer 2

M A Srinivas

SSC-Addicted

Points: 494

February 10, 2014 at 3:22 am

#1687467

I forgot to mention . This is in SQL 2005 SP2

SQLCJ SSCommitted Points: 1791 More actions · Answer 3

I got 7 and 8,8 on .. 2008(RTM) developers and enterprise edition ... I'm stumped too... can somebody please explain the reason behind this output ?

Luis Cazares SSC Guru Points: 183706 More actions · Answer 4

You should get 8 on both queries. A MAX() on a ROW_NUMBER() without PARTITION BY should give you the same values as COUNT(*).

The reason is that you have keyids 1 and 8 repeated. You could check it with a simple query.

SELECT *

from @a a

left outer join @b-2 b

on a.keyid = b.keyid

Luis C.
General Disclaimer:
Are you seriously taking the advice and code from someone from the internet without testing it? Do you at least understand it? Or can it easily kill your server?

How to post data/code on a forum to get the best help: Option 1 / Option 2

SQLCJ SSCommitted Points: 1791 More actions · Answer 5

Exactly... that is what I tried before posting reply... it clearly shows that it should give 8 as an output but I did not get it... am I missing something here ?

Umer Akram SSC-Insane Points: 22209 More actions · Answer 6

MAX() is working upon as per the definition of the base table.

in your query u are using left join, if you try to use right join u will be even more surprised.

Once you are done with the surprised run the below query

declare @a table( keyid int,keyname varchar(50) )

declare @b-2 table( keyid int,keyname varchar(50) )

declare @C table( akeyid int,akeyname varchar(50), bkeyid int, bkeyname varchar(50) ,rowasc int )

insert into @a values (1,'10')

insert into @a values (2,'20')

insert into @a values (4,'40')

insert into @a values (6,'60')

insert into @a values (8,'80')

insert into @a values (9,'90')

insert into @b-2 values (1,'100')

insert into @b-2 values (3,'300')

insert into @b-2 values (5,'500')

insert into @b-2 values (6,'600')

insert into @b-2 values (8,'800')

insert into @b-2 values (8,'801')

INSERT into @C

select a.keyid as akeyid,a.keyname as akeyname , b.keyid as bkeyid ,b.keyname as bkeyname,

row_number() over( order by a.keyid asc ) as rowasc

from @a a

left join @b-2 b on a.keyid = b.keyid

SELECT MAX(rowasc), COUNT(akeyid)

from @C

SELECT MAX(rowasc)

from @C

Its a bug in 2005, 2008, 2008R2 .... but its running perfectly on the 2012. :w00t:

here is the link http://support.microsoft.com/kb/2565683

kindly upgrade your sql server to latest SPs if possible.

SQLCJ SSCommitted Points: 1791 More actions · Answer 7

Thank you for that Service pack was applied and got my Inner peace...