In my example, $result is simply the return value of fetchrow_array() - I.e. a single row of data with a single column. Note that a single query can return multiple rows of results:

while (my ($col1,$col2) = $sth->fetchrow_array()) {
  # ...
}
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Using placeholders doesn't have any direct influence on how you fetch the results. It only influences how you prepare and execute the query before reading the results.

Note that using placeholders like this splits up the process in three distinct steps:

1. preparing the query (with the question marks as placeholder marking input values). - this gives you a statement handle.
2. executing the query from the statement handle (where you need to supply the values for each place-holder)
3. fetching the results of the executed query from the statement handle.

I think I understand this a lot better now, thank you.
I have one more related quick question.
In my first statement the where on SSN has a % sign on it, because the user only enters the last 4 digits, how do I do this with placeholders?
The original line was:and SSN like '%$ssn'
Here is my new SQL with placeholders:


my $sql = <<"END"
SELECT
  SSN, RTRIM(LAST_NAME,' '),
  TO_CHAR(BIRTH_DATE,'YYYY'),
  STORE
FROM
  PYHADMIN.PY_EMP_SHADOW
where
      TO_CHAR(BIRTH_DATE,'YYYY') like ?
  and SSN like ?
  and RTRIM(LAST_NAME,'  ') like upper(?)
  and rownum <= 1
END
;
my $yi = $dbh->prepare($sql);
$yi->execute($year, $ssn, $name);
#--------Send the values from the query into variables
($SSNc, $LAST_NAMEc, $YEARc, $storenum) = $yi->fetchrow_array;
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IIRC you will have to put the "%" sign in the the argument to execute() yourself, since placeholders only handle quoting, they don't try to parse anything else:

$yi->execute($year,"%".$ssn,$name);
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Note that that also means you have to be careful about what's in $ssn - if someone manages to put "_" or "%" characters in $ssn the query might no longer do what you think it should.
"What should it profit a man, if he should win a flame war, yet lose his cool?"