using has_selected_record() of Net::MySQL

ranjan_jajodia has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks,
I have written a script which checks if an id is already present in the database and depending on that it does other things. Following is the part of the code where i have confusion:

$mysql->query(q{select id from id_table where id = '1'});
if ( $mysql->has_selected_record) {
   #do something;
} else {
   #do something else
}
[download]

In the above 'if loop', the condition always return true even if the id is not present in the table. Am i misunderstanding the use of 'has_selected_record()'? If yes how do i know whether the query has returned result or not? I understand I can create an iterator and get the exact result but i don't think that is needed because
1) I don't want the result- I just want to know whether there is a result or not.
2) The query will be excuted a lot of times and creating iterator each time will not be resource friendly.
I have gone throught the documentation present at CPAN along with the module Net::MySQL but unfortunately did not get much info. Could you please clear my doubt?

Regards,
Ranjan

--Let Logic Rule--

Comment on using has_selected_record() of Net::MySQL Download Code

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Re: using has_selected_record() of Net::MySQL by critter (Acolyte) on Aug 11, 2005 at 11:54 UTC
Hi, Maybe you can check on how many records you get returned. The CPAN pages mentions the next function: `my $affected_rows = $mysql->get_affected_rows_length;` [download] I'm guessing that the has_selected_record returns always true because it can be run and will always return a value. I've never used this module but you could check and see what you get as return value. If this is a number you could change your check a bit perhaps to: `if ( $mysql->has_selected_record > 1 ) { #do something; } else { #do something else }` [download] Just my 2 cents, Grtz, Critter	[reply] [d/l] [select]
Re^2: using has_selected_record() of Net::MySQL by ranjan_jajodia (Monk) on Aug 11, 2005 at 13:39 UTC
Hi, get_affected_rows_length() will work only in case of 'update queries'. In 'select queries it will always return zero. has_selected_record() returns true or false as written in the specifications at CPAN. Thanks for the effor though :-), Ranjan --Let Logic Rule--	[reply]