my @columns = qw(username password first last email phone 
                 address city state zip country 
                 s_address s_city s_state s_zip s_country
                 intrests);

# There are more elegant ways to build this, but this is
# a step-by-step way :
my $sql_columns = "id";
my $sql_values = "''";
foreach @columns {
  $sql_columns .= ", $_"; # Add the column name
  $sql_values .= ", ?"; # And add a parameter to the query
};

$sth = $dbh->prepare( "INSERT INTO users($sql_columns) VALUES ($sql_values)");

# Now extract each CGI parameter, and store the values in @formvalues
my @formvalues = map { param( $_ ) } @columns;

$sth->execute(@formvalues);