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sybperl-l Archive
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From: Michael Peppler <mpeppler at MBAY dot NET>
Subject: Re: Queries n rows at a time
Date: Jul 15 1998 2:42PM
Simon Yaminian writes:
>
> >
> > It depends on the query. If there's a unique field, you can use it to
> > chop your query into blocks. eg
> >
> > select id, name, address from employees
> > where state='NY' and id>$x and id<=$x+100
> >
> >
> Thanks for your reply.
> Suppose you have the following query:
>
> select * from employees
>
> How can you get those let's say 200 at a time and suppose you have 20,000
> employees. The idea is, instead of waiting let's say 20 seconds to complete
> the query, wait .2 second at a time and get some data to work with in the
> meantime.
If you have an appropriate index you don't have to wait 20 seconds to
get data back.
But assuming you have a unique index on employee_id, you could do:
set rowcount 200
$data = $dbh->sql("select * from employee");
# do something with the data...
$last_employee_id = $data[$#{$data}]->[0]; # assume employee_id is
# column 0
$data = $dbh->sql("select * from employee where employee_id >
$last_employee_id");
etc...
You can put this in a loop to make it nicer.
Michael
--
Michael Peppler -||- Data Migrations Inc.
mpeppler@datamig.com -||- http://www.mbay.net/~mpeppler
Int. Sybase User Group -||- http://www.isug.com
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