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Re: SQL Results

by jsegal (Friar)
on Feb 11, 2002 at 17:11 UTC ( [id://144717]=note: print w/replies, xml ) Need Help??

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in reply to SQL Results

If the emails are exact, you could use "distinct" in your SQL statement. E.G. something like
select distinct E_mail from table where <conditions>
That would be the easiest approach -- let the database do the work. You could do the same work in perl using a hash to keep track of the addresses, ingoring the values of the hash.

e.g. something like (in pseudo-perl)
my %emailhash = (); foreach $row (result_set) { $emailhash{$row->{email}} = 1; } my @unique_emails = keys %emailhash;
Using a hash where you only care about the keys (setting the values to 1) is a common idiom for ensuring uniqueness from a list when you don't care about the order. A concise form of this idiom would be
%temp_hash = map {$_ => 1} @non_unique_list; @unique_list = keys (%temp_hash); # or @unique_list = sort keys (%temp_hash);
The latter case can be used if you want the list ordered, and can extract the order from the values of the entries themselves.

Hope this helps...

-JAS

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