In DBI, it (fetchrow_hashref, not fetchhash) returns a hash where the
keys = column names and values = value of the columns on the row. I
consider it a generaly bad thing since it forces you to alias your
columns when you have two (or more) columns with the same name or an
expersion as a column in you result set.
select a.id,
a.name,
a.create_date,
b.purchase_amount,
b.create_date,
b.create_date - a.create_date
from customer a, purchase b
where a.id = b.id;
has column names of qw(id, name, create_date, purchase_amount,
create_date, expression). When DBI assigns data to the hash the code
would look like this:
$hash{id} = $row[0];
$hash{name} = $row[1];
$hash{create_date} = $row[2];
$hash{purchase_amount} = $row[3];
$hash{create_date} = $row[4];
$hash{expression} = $row[5];
as you can see we lose the first create_date since it is overwritten by
the second, and goddess help us if we have more than one expression. To
fix this we must alias the column names:
select a.id as a_id,
a.name as a_name,
a.create_date as a_create_date,
b.purchase_amount as b_purchase_amount,
b.create_date as b_create_date,
b.create_date - a.create_date as interval_between
from customer a, purchase b
where a.id = b.id;
Frankly I prefer to work with the array ref I get back from
fetchrow_arrayref or the array I get back from fetchrow_array.
$sth->execute;
while (($id, $cust_name, $cust_create_date, $ammount, $bought_on,
$time_diff) = $sth->fetchrow_array) {
do stuff
}
$sth->finish;
On 07 Jun 2001 16:34:48 -0400, Bradshaw, Brian wrote:
> You guys have been so nice.. I have another question :)
>
> What does fetchhash do?
>
> I have the code :
> $return_hash = $dbh->query($query) or print "$query\n\n";
> %result = $return_hash->fetchhash();
> But I am unsore of what the fetchhash does.
>
> Thanks again!
>
> Brian Bradshaw
> Systems Engineer
> McGraw-Hill Education
> McGraw-Hill Companies
> 860-409-2603
> [EMAIL PROTECTED]
>
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Kallisti!
