Just mentioning $db[$vars{_recNo}]{'name'} might make it spring to life. It's a process known as "autovivification" ("automatic bringing to life", or somesuch). Note this little testscript:

use Data::Dumper;
my %vars = ( _recNo => 3 );
my @db;
(undef) = $db[$vars{_recNo}]{'name'};
print Dumper \@db;
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Resulting in:

$VAR1 = [
          undef,
          ${\$VAR1->[0]},
          ${\$VAR1->[0]},
          {}
        ];
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Never mind the ${\$VAR1->[0]}, it's just Data::Dumper's silly way of saying it's uninitialized (the "same" undef value as the first array item), but trying to check a (nonexistent) field in what isn't even a hash, makes the hash spring to life. That's why you see an empty anonymous hash there, as a fourth array element.

Searching through Google for perl autovivify OR autovivification brings up this article as a first hit: Autovivification : What Is It and Why Do I Care?.