RE: [SPAM] RE: SQL - Updates with joins

["Elvis Budimlic" <ebudimlic@xxxxxxxxxxxxxxxxxxxxxxxxx>]

Standard SQL Update Join syntax is really funky.  Microsoft has some
non-standard but elegant and intuitive SQL syntax.
IBM sticks with standards so we have to as well :)
On the good note, following standards ensures your code is portable so I'm
not going to complain.

That particular subselect is doing your join between r1 & r2 and I'm using
EXISTS in the main WHERE clause to make sure only rows where there was a
match found for r1 are updated.  You're not using any of the fields from r2
in the actual update (SET) part, so I chose to project a literal from the
inner join subselect.
Something HAS to be projected from the SELECT and literal 1 is as good as
anything else.  I suppose you could use 'MATCH' or 'FOUND' literals to
illustrate this intention more clearly.
When there's no match found you'll get a NULL value projected out of
subselect and anything compared with NULL will evaluate to False (even NULL
against NULL evaluates to False).

Hope I didn't confuse the issue even further with this :)

Elvis

-----Original Message-----
Subject: [SPAM] RE: SQL - Updates with joins

Elvis, what does this 1 represent?

EXISTS (SELECT 1

-----Original Message-----
Subject: RE: SQL - Updates with joins

Joined file SQL view is likely to be read-only, hence it would not
updateable.
John needs to review UPDATE syntax a bit as there is no FROM in the base
UPDATE syntax (there is in subselects, which are often used in UPDATEs for
join purposes).
I'll give it a go for your UPDATE statement, but make sure you test it first
John:

UPDATE rugd80dat.asbacpp r1
SET bai1tx = 'N', bai2tx = 'N'
WHERE (r1.baartx = 'APV' or r1.baartx = 'MPV' or r1.baartx = 'SPV' or
r1.baartx = 'EPV')
AND r1.bai1tx = ' ' and r1.bai2tx = ' ' AND 
EXISTS (SELECT 1 FROM rugd80dat.pmsp0200 r2
WHERE r1.baartx = r2.symbol and r1.baastx = r2.policy0num and r1.baadnb =
r2.module AND r2.trans0stat = 'V' and r2.renewal0cd = '1')

Elvis

-----Original Message-----
Subject: Re: SQL - Updates with joins

I've never seen an update statement with a FROM clause or a JOIN for that
matter.   I suggest creating a view that combines the two files and then
run the update over the new view.

Michael Schutte
Work 614-492-7419
email  michael_schutte@xxxxxxxxxxxx


                                                                           
             "John Candidi"                                                
             <jacandidi@rutger                                             
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I am having a problem generating the correct SQL script run in iSeries
Navigator.



This is what I have so far:



Update rugd80dat.asbacpp

set bai1tx = 'N', bai2tx = 'N'

from rugd80dat.asbacpp r1,rugd80dat.pmsp0200 r2

where (r1.baartx = r2.symbol and r1.baastx = r2.policy0num and r1.baadnb =
r2.module)

and (r1.baartx = 'APV' or  r1.

baartx = 'MPV' or r1.baartx = 'SPV' or r1.baartx = 'EPV')

and (r1.bai1tx = ' ' and r1.bai2tx = ' ')

and (r2.trans0stat = 'V' and r2.renewal0cd = '1')

When run as a select statement, it returns the correct rows.  When changed
to do the actual update, it reports an unexpected 'from'.  Any
recommendations?  I tried with a 'where exists' with a select subquery, but
it ended up hitting all the rows in the asbacpp table, not just the handful
in the query result.



John A Candidi

Rutgers Insurance Companies

IT Director - AS/400 Manager

856-779-2274