Re: AW: Quick SQL expression evaluation

The "String = 'Values(Select count(*) from Item) into ?';" did work.
Thanks, very cool. I had never scene the VALUES() usage.

I understand the points of using static SQL, but I'm building a pretty
complex SQL SELECT, that I'm never sure about how it will be used.
Basically, we're taking
filter parameters and constructing our SELECT. These filters also include
OP-CODES (=, >, <>, etc), so I never REALLY know the SQL is going to be
used.

David

David L. Mosley, Jr.
Technical Solutions Architect
Dancik International, Ltd.
2000 CentreGreen Way, Suite 250
Cary, NC 27513

www.dancik.com



"Birgitta Hauser" <Hauser@xxxxxxxxxxxxxxx>
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05/26/2010 01:01 AM
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RPG programming on the IBM i / System i <rpg400-l@xxxxxxxxxxxx>


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Subject
AW: Quick SQL expression evaluation






If you want to do an Select ... into dynamically, why not using something
like this?

/Free
String = 'Values(Select count(*) from Item) into ?';
//Or
String = 'Values(' + MySelectStmt + ') into ?';

/Exec SQL Prepare DynSQL from :String;
/Exec SQL Execute DynSQL using :MyResult;

/End-Free

In either way I'd use static SQL whenever possible. With static SQL an
access plan gets stored into the (service-)program object, that can be
validated at runtime. With dynamic SQL the string must be converted into
an executable SQL statement at runtime, an access plan must be created by
scratch (if not stored in the SQL plan cache or already in the job's
cache), additional steps at runtime that are not necessary for static SQL.

For multiple selections you may also use:

... Select Fld1, Fld2, .... FldN
From MyTables ...
Where Fld1 = Case When :EnterFld1 <> 0 then :EnterFld1
else Fld1
And Fld7 = Case When :EnterFld7 <> ' ' or :EnterFld7 is not
NULL Then :EnterFld7 Else Fld7 End,
And Fld8 = Case When :EnterFld8 between '0001-01-02' and
'9999-12-31' then :EnterFld8 else Fld8 End
...

Mit freundlichen GrÃÃen / Best regards

Birgitta Hauser

"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!"

-----UrsprÃngliche Nachricht-----
Von: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx]
Im Auftrag von dmosley@xxxxxxxxxx
Gesendet: Tuesday, 25. May 2010 16:10
An: RPG programming on the IBM i / System i
Cc: RPG programming on the IBM i / System i; rpg400-l-bounces@xxxxxxxxxxxx
Betreff: Re: Quick SQL expression evaluation

That's an interesting trick. I would have hoped that some like using
"SELECT COUNT(*) INTO ? FROM ITEM" would work the same.

/Free
String = 'SELECT COUNT(*) INTO ? FROM ITEM';
/Exec SQL Prepare DynSQL From :String;
/Exec SQL Execute DynSQL using :MyResult;
Dsply MyResult;
/End-Free

David L. Mosley, Jr.
Technical Solutions Architect
Dancik International, Ltd.
2000 CentreGreen Way, Suite 250
Cary, NC 27513

www.dancik.com



Luis Rodriguez <luisro58@xxxxxxxxx>
Sent by: rpg400-l-bounces@xxxxxxxxxxxx
05/25/2010 05:04 AM
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RPG programming on the IBM i / System i <rpg400-l@xxxxxxxxxxxx>


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Re: Quick SQL expression evaluation






Wow!! Thanks Birgitta!! ..

One can always trust that you will find the solution to almost any SQL
problem, this one will go into the archives.


Best Regards,

Luis Rodriguez
IBM Certified Systems Expert â eServer i5 iSeries


On Tue, May 25, 2010 at 8:21 AM, Birgitta Hauser
<Hauser@xxxxxxxxxxxxxxx>wrote:

Try the following:

D MyResult S 11P 2
D String S 256A Varying
D Expr S 256A Varying inz('2 + 2')
/Free
String = 'Values(' + Expr + ') into ?';
/Exec SQL Prepare DynSQL From :String;
/Exec SQL Execute DynSQL using :MyResult;
Dsply MyResult;
/End-Free




Mit freundlichen GrÃÃen / Best regards

Birgitta Hauser

"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!"

-----UrsprÃngliche Nachricht-----
Von: rpg400-l-bounces@xxxxxxxxxxxx

[mailto:rpg400-l-bounces@xxxxxxxxxxxx]

Im
Auftrag von Dennis Lovelady
Gesendet: Tuesday, 25. May 2010 14:30
An: 'RPG programming on the IBM i / System i'
Betreff: Quick SQL expression evaluation

I am trying to write a procedure I thought would be extremely simple: a
short SQL evaluation program that would simply take an expression and
return
the result of SQL operating on that expression. For a silly example:

Exec sql set :myResult = 2 + 2 ;



To minimize complexity, I am passing the '2 + 2' part as a string, so

that

the meat of this very short procedure is:

Exec sql setl :myResult = :myExpression ;



But (and, yes, I know I should have expected this) SQL is seeing it as

the

string "2 + 2" rather than a pair of values with an operator between

them.

Is there an SQL verb/clause that informs the SQL processor that the
following is an expression rather than a string (such as with unix'

"expr"

command)? Or is this just a pipe dream, not worth the effort?



Dennis E. Lovelady
AIM/Skype: delovelady MSN: fastcounter@xxxxxxxxxxxx
<http://www.linkedin.com/in/dennislovelady>
www.linkedin.com/in/dennislovelady --
You can't have everything. Where would you put it?



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