How to fetch n rows at a time?

I know that I can use the rownum function to return n rows at a time, but the rownum function will be applied after all rows are returned by the query, which is bad for performance since my table has lot of rows. What I need is really to fetch n rows at a time from the DB.
Regards

I am not sure what you mean by "the rownum function will be applied after all rows are returned by the query", but that appears to be an incorrect statement. If you have a ROWNUM limit in a query, Oracle knows that it only has to fetch the first M rows.
If you are looking for an ability to page through query results, there is an AskTom thread on pagination in SQL.
This would only be appropriate, though, if you expect that users will only ever want the first few pages of results (i.e. users of Google aren't going to look through every page of results for generic search terms, they are going to look at page 1, maybe page 2 and page 3, and then stop). If the application is going to process all the rows that the query returns, you'd need some other construct and we would need some additional requirements. Your client application can probably fetch N rows at a time. If the client is PL/SQL, a BULK COLLECT with a LIMIT clause may also be appropriate.
Justin

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declare
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c1 varchar2(30);
c2 number;
c3 date;
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Hi,
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I want to display the rows number of times as the value exists in num column in the below query
with t AS
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     UNION ALL
     SELECT 'prasad' NAME, 'hyd' LOC, 3 NUM FROM DUAL
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Nag Aswadhati wrote:
Hi All,
I want to display the rows number of times as the value exists in num column in the below query
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with t AS
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select t.name, t.loc
from t
connect by level <= num
         and name = prior name
         and (prior sys_guid() is not null);
NAME      LOC
krishna   hyd
prasad    hyd
prasad    hyd
prasad    hyd
venkatesh hyd
venkatesh hyd
6 rows selected

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2 /
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5 /
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2 /
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2     ltime integer;
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10     dbms_output.put_line('Exec Time:'||ltime/100||' Seconds...');
11
12     commit;
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5 01:00
6 01:00
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I have one more question.
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<view id="FetchRows">
     <![CDATA[ istream(select * from mdepthChannel)
                 ]]>
</view>
<query id="ExampleQuery">
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Sri
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With dynamic CreateViewObject How To "Navigate N rows at a time using DataTags" fails

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ml
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moreover,
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on second click on next set, records from 11 to 20 are displayed.
on third or N'th click on next set, records from 11 to 20 are
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Oops, but this will work, won't it?
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Often the situation is such that you have multiple courses across a range of dates.So students may take more than one course, and you need to track attendance for each course date. The following graphic demonstrates this:
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How to fetch n rows at a time?

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