jeffa is right on.

Working with hashes, both on the input side and select side is easy:

my $stmt = 'INSERT INTO some_table (' . join(',', keys %data_to_insert
+) . ') VALUES (' . join(',', ('?') x keys %data_to_insert) . ')';
$dbh->do( $stmt, undef, values %data_to_insert);
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and selecting it:

my $stmt = 'SELECT * FROM some_table WHERE entry_id = ?';
my $row = $dbh->selectrow_hashref($stmt, undef, $entry_id);

my $full_name = $row->{first_name'} . ' ' . $row->{last_name'};
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Be sure to see gmax's wonderful DBI Recipes.