I have a list of userid's in an array. I have a DBI table. I want to find out which ID's in my array exist in my table.

I have about three work-arounds for this problem, but all of them are time consuming and a big drain on resources. I was wondering if any of you have come up with an easy way to compare the contents of a list (array) against a table (Perl:DBI:MySQL).

At the risk of looking like an idiot, here is one of my previous work-arounds:

I have a list of userid's (@compare_array) that i want to compare to my subscription table.

$primer=$dbh->prepare("SELECT count(*) FROM subscription where userid=
+? ");

foreach $userid (@compare_array){
    $primer->execute($userid);
      if ($primer->err()){$message.=$primer->errstr(); &shellout; exit
+;}
       ($count)=$primer->fetchrow_array();

           if($count > 0){#there is a match
                    }else{#there was no match
                    }
}

[download]

The above system WORKS, and works pretty well for tables of <1000 records. But when I'm dealing with 10,000 or 50,000 records, this search becomes an incredible drain.
Is there a way to perform this operation without running 25,000 SELECTs when @compare_array has that many ID's?

-oakbox.com

"If what I'm saying doesn't make sense, that's because sense cannot be made, it's something that must be sensed"
-J.S. Hall

In reply to Comparing an array to a DBI table by oakbox

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