Very good question, and very good answer ... but it's hard to grok straight out of the docs. In the case of $dbh->do() ... i never use the attribute hash, which is why it is set to undef. It kinda gets in the way, but it is a small price to pay for the gain. I use the attribute hash when i am fetching rows from the DB. Here is a quick example, just replace the query with one of your own: 
use DBI;
use Data::Dumper;

...

my $query = 'select * from foo';
my %attr  = ( Slice => {} );
print Dumper $dbh->selectall_arrayref($query);
print Dumper $dbh->selectall_arrayref($query, \%attr);

[download]
The first DBI call returns a two dimensional array, or as we like to call it in Perl, a List of Lists (LoL). This is a nice "snapshot" of the table that is returned, one of the coolest features of Database programming in Perl.

The second DBI call returns something even cooler. A List of Hashes (LoH). Each hash contains key/value pairs of the column name and its value for the current row. Just run the code and you should see what i mean. :)

What's great about the second call is that you can then pass the results straight to your Templating Engine of choice, such as HTML::Template or Template. I gave another example over at Re: DBI fetchrow_hashref issue. Fun stuff.

UPDATE: you are welcome zigdon, but credit where credit is due, i learned this from gmax.

jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)

In reply to 3Re: Perl Beginners problem with DBI by jeffa
in thread Perl Beginners problem with DBI by Anonymous Monk

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