# Note: reordered where clause
# to put quick to evaluate conditions first
# the query has a better chance of actually being optimized

my $statement = <<EOF;

SELECT name, last_name, reg_num, month, year
FROM   members
WHERE  year='2009'
       AND LIST_POSITION(month, $month_values)
          = LIST_POSITION(reg_num, $reg_num_values)
EOF