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MQSeries.net Forum Index » WebSphere Message Broker (ACE) Support » fetching n rows from the db

fetching n rows from the db

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ashkalp

Posted: Fri Jun 27, 2014 2:26 am Post subject: fetching n rows from the db

Newbie

Joined: 27 Jun 2014
Posts: 1

I am using DatabaseInput node to read the records/Events from the oracle db. I want to fetch n records from the db based on some condition. But i am unable to do it. In ReadEvent I use:
SET NewEvents.Event[] = SELECT AE_EVENT_STORE.* AS Usr, AE_EVENT_STORE.PRIMARYKEY AS Key FROM CMS_MELLON.AE_EVENT_STORE
WHERE AE_EVENT_STORE.BATCH_FLAG = 'I' AND (AE_EVENT_STORE.PROCESSED IS NULL OR AE_EVENT_STORE.PROCESSED = 'N')AND ROWNUM<=100;

In BuildMessage i write:
SET Root.DataObject.AE_EVENT_DATA[] = SELECT AE_EVENT_DATA.* FROM Database.CMS_MELLON.AE_EVENT_DATA WHERE AE_EVENT_DATA.CONTEXTIDGUID = DispatchedEvent.Usr.PRIMARYKEY;

Here I want to fetch 100 records only, but my code does not work. Please reply.

smdavies99

Posted: Fri Jun 27, 2014 3:27 am Post subject:

Jedi Council

Joined: 10 Feb 2003
Posts: 6076
Location: Somewhere over the Rainbow this side of Never-never land.

You may not be able to do it via an ESQL Select.

you may have to drop into the DB SQL using a Passthru.

for example on SQLServer, you could write a select

Code:

select top 100 * ... from .... where

DB2 and Oracle have their own ways to do this.
_________________
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Every time you reinvent the wheel the more square it gets (anon). If in doubt think and investigate before you ask silly questions.

mqjeff

Posted: Fri Jun 27, 2014 5:01 am Post subject:

Grand Master

Joined: 25 Jun 2008
Posts: 17447

While smdavies99's suggestion is helpful, it may not actually apply here.

BuildMessage is going to be called once for each individual Event that you put into NewEvent.

What you are doing in your ReadEvent is fetching N rows each DatabaseInput node polling interval and sending each row to BuildMessage to be propagated out of DatabaseInput node.

So if you want each message propagated out of DatabaseInput to contain N rows, then you need to change the query in BuildMessage to use N rows, rather than using ReadEvent.

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