RE: Limiting SQL results returned -- MIDRANGE-L

Good catch Elvis!

I missed deleting that.

Charles

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Elvis Budimlic
Sent: Wednesday, August 01, 2007 10:14 AM
To: 'Midrange Systems Technical Discussion'
Subject: RE: Limiting SQL results returned

What Charles has should work for you Jim, just take out the
2nd WITH clause (CTEs list only requires WITH at the
beginning of the list).

Elvis

Celebrating 10-Years of SQL Performance Excellence
http://centerfieldtechnology.com/training.asp

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Wilt, Charles
Sent: Wednesday, August 01, 2007 7:10 AM
To: Midrange Systems Technical Discussion
Subject: RE: Limiting SQL results returned

Jim,

Off the top of my head....

With T1 as (select status, infoField, rand() as randomNbr
from filename
),
With T2 AS (SELECT Status,
InfoField,
ROW_NUMBER() over (PARTITION BY Status ORDER BY Status,
randomNbr) as Nbr
from T1 ORDER BY Status )

SELECT * FROM T2 WHERE Nbr < 6

Sorry, don't have v5r4 to test against.

HTH,
Charles

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Jim Essinger
Sent: Tuesday, July 31, 2007 7:02 PM
To: Midrange Systems Technical Discussion
Subject: Re: Limiting SQL results returned

This list is great!

Elvis

Thanks for pointing me in the right direction.

After doing it the hard way, this worked for me;

With T1 AS (SELECT Status,
InfoField,
ROW_NUMBER() over (PARTITION BY Status ORDER BY Status) as Nbr
from FileName ORDER BY Status )

SELECT * FROM T1 WHERE Nbr < 6

Any thoughts on how to get a random 5 selected instead of

the first 5?

Thanks again.

Jim

On 7/31/07, Elvis Budimlic
<ebudimlic@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

Looks like ROW_NUMBER would work. Try this in Run Sql Scripts if
you're on
V5R4:

SELECT * FROM
(SELECT A.*,
ROW_NUMBER() OVER(PARTITION BY status ORDER BY

status) AS RN

FROM myfile A) B
WHERE RN IN (1,2,3,4,5)

or using common table expression:

WITH CTE AS
(SELECT A.*,
ROW_NUMBER() OVER(PARTITION BY status ORDER BY

status) AS RN

FROM myfile A)
SELECT * FROM CTE WHERE RN IN (1,2,3,4,5)

NOTE: It errored out on my system, but we're way behind on

db fixpacks.

Elvis

Celebrating 10-Years of SQL Performance Excellence
http://centerfieldtechnology.com/training.asp

-----Original Message-----
Subject: RE: Limiting SQL results returned

Scratch that syntax, I just realized it won't work. Try

this instead

WITH CTE1 AS
(SELECT * FROM MYFILE WHERE STATUS = 'status 1' FETCH

FIRST 5 ROWS

ONLY),
CTE2 AS
(SELECT * FROM MYFILE WHERE STATUS = 'status 2' FETCH

FIRST 5 ROWS

ONLY),
CTE3 AS
(SELECT * FROM MYFILE WHERE STATUS = 'status 1' FETCH

FIRST 5 ROWS

ONLY), ......
SELECT * FROM CTE1
UNION ALL
SELECT * FROM CTE2
UNION ALL
SELECT * FROM CTE3
....

Ugly, I know.

Celebrating 10-Years of SQL Performance Excellence
http://centerfieldtechnology.com/training.asp

-----Original Message-----
Subject: RE: Limiting SQL results returned

Brute force it by running something like:

SELECT * FROM MYFILE WHERE STATUS = 'status 1' FETCH FIRST

5 ROWS ONLY

UNION ALL SELECT * FROM MYFILE WHERE STATUS = 'status 2'

FETCH FIRST 5

ROWS ONLY UNION ALL SELECT * FROM MYFILE WHERE STATUS =

'status 1'

FETCH FIRST 5 ROWS ONLY ......

and do it as many times as you have unique statuses in your

table (you

said about 20 or so).

I haven't used new RANK, PARTITION and recursive CTEs yet

so I'm not

sure if there is more elegant way to address this.
I'd be curious to see one as well.

Elvis

-----Original Message-----
Subject: Limiting SQL results returned

SQL Guru's

Is there a way to limit the number of rows returned from a

SQL statement?

For instance, I want a sampling of 5 records for each

status from a file.

Status, Fn1, .... Fn6

For _each_ status that appears in the file, I want 5 and only 5
resulting rows, could be the first 5 or last 5 or a random 5 -
although a random 5 would be awesome - would help with

another project I have ahead of me.

There could be 20 different status codes in the file, and I

want 5 records

for all 20 status codes. I guess that there might not be

5 for some

statuses, so getting up to 5 results would be OK too.

Any thoughts?

Jim

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