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  2. RPG400-L
  3. June 2023

Re: SQL question on embedded varaibles

Hi Birgitta,

that’s what I also think all the time - but from my experience often a sub-select performs better than a LIKE predicate - at least in our environment.

I don’t have the exact environment of the OP but I will try to run both solutions in our environment and look what Visual Explain says to both.

The sub-select and the SPLIT table function should be very costly but it’s only performed once and the result table is cached. And the LIKE pattern has to be matched against every row - but I don’t know how good the optimization is there.

Well I’m very exited to see how it will go out. Right now I would bet on the LIKE to be faster - but that doesn’t mean too much.

Regards,
Daniel




Von meinem iPhone gesendet
Am 25.06.2023 um 18:35 schrieb Birgitta Hauser <Hauser@xxxxxxxxxxxxxxx>:

... but an unneeded SELECT statement costs performance!

Another solution could be:

WSubA = 'AA,AB,AC,AD,AE,';

Exec SQL
SELECT LOC INTO :wLOC
FROM LOCATION
WHERE LTYP NOT IN ('F','H','I','O','B')
AND :WSubA like '%' concat Trim(SUBA) concat ',%'
AND PALT = :wPALT;

Note: With this solution also no index built over SUBA can be used!

Mit freundlichen Grüßen / Best regards

Birgitta Hauser
Modernization – Education – Consulting on IBM i

IBM Champion since 2020

"Shoot for the moon, even if you miss, you'll land among the stars." (Les Brown)
"If you think education is expensive, try ignorance." (Derek Bok)
"What is worse than training your staff and losing them? Not training them and keeping them!"
"Train people well enough so they can leave, treat them well enough so they don't want to. " (Richard Branson)
"Learning is experience … everything else is only information!" (Albert Einstein)

-----Original Message-----
From: RPG400-L <rpg400-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf Of Daniel Gross
Sent: Sunday, 25 June 2023 14:58
To: RPG programming on IBM i <rpg400-l@xxxxxxxxxxxxxxxxxx>
Subject: Re: SQL question on embedded varaibles

Hi Liam,

Darryl and Birgitta are right - what you want to do is not possible the way you try it, and dynamic SQL is often used, to solve this problem.

But ... dynamic SQL ist not the only solution. You can also use the SYSTOOLS.SPLIT table function, to split your variable in individual values.

EXEC SQL SELECT LOC INTO :wLOC
FROM LOCATION
WHERE LTYP NOT IN ('F','H','I','O','B')
AND SUBA IN (
select trim(both '''' from varchar(element, 5))
from table(systools.split( :wSUBA , ','))
)
AND PALT = :wPALT;

If I recalled the syntax of SPLIT and TRIM correctly (I don't give a guarantee) then the sub-select should split your list

'AA ','AB ','AC ','AD ','AE'

into

'AA '
'AB '
'AC '
'AD '
'AE'

Now I thought, that the quotes were just for the list, and you wanted to compare without the quotes - so the TRIM function is used to strip of those quote chars.

And then - the IN operator works on the result table like with any other SQL sub-select.

Just try it out interactively.

HTH

Regards,
Daniel


Am 25.06.2023 um 14:32 schrieb Birgitta Hauser <Hauser@xxxxxxxxxxxxxxx>:

This IN (:wSUBA) will not work with static SQL.
Each option has to be passed as a variable, i.e. IN(:VAR1, :VAR2,
:VAR3,
:VAR4)

... alternatively you can use dynamic SQL and then embed your variable
in the SQL statement to be prepared.

Mit freundlichen Grüßen / Best regards

Birgitta Hauser
Modernization – Education – Consulting on IBM i

IBM Champion since 2020

"Shoot for the moon, even if you miss, you'll land among the stars."
(Les
Brown)
"If you think education is expensive, try ignorance." (Derek Bok)
"What is worse than training your staff and losing them? Not training
them and keeping them!"
"Train people well enough so they can leave, treat them well enough so
they don't want to. " (Richard Branson) "Learning is experience …
everything else is only information!" (Albert
Einstein)

-----Original Message-----
From: RPG400-L <rpg400-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf Of liam
henderson
Sent: Friday, 23 June 2023 18:23
To: rpg400-l@xxxxxxxxxxxxxxxxxx
Subject: SQL question on embedded varaibles

Hi,
I'm trying to use a variable to list some values that I want to use on
an IN statement on my WHERE clause but don't seem to able to get it quite right.
Interactive SQL returns a result but the program doesn't It returns
SQLSTATE='02000' SQLCODE=100

EXEC SQL
SELECT LOC INTO :wLOC
FROM LOCATION
WHERE LTYP NOT IN ('F','H','I','O','B') AND
SUBA IN (:wSUBA) AND
PALT = :wPALT

The string :wSUBA is formatted as 'AA ','AB ','AC ','AD ','AE'
I tried moving the brackets into the string but that didn't work I
also tried removing the quotes and just comma separating but that
didn't work Is what I'm doing even possible or do I need to split them
out and check one by one?
I'm probably doing something really stupid.
Any help much appreciated.
Regards.
Liam.
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