perl mysql dbi : multiple ways to fetch record. (hash, array, all)

Here are the ways to fetch record from mysql

 my $row  = $sth->fetchrow_arrayref;
my $rows = fetch_rows( $dbh, 'SELECT * FROM TABLE' );
my $row  = $sth->fetchrow_arrayref;
          fetch_insert_id()
 @row_ary = $sth->fetchrow_array;
$ary_ref = $sth->fetchrow_arrayref;
$sys_row = $sts->fetchrow_hashref
$ary_ref = $sth->fetchall_arrayref; 

Ajax: A New Approach to Web Applications

Hey Guies,
Do you got any time a question about what technologies are being used by google for making Gmail, Google Suggest, Google Maps such a GUI rich web application?
But I was always?
And i found the answer Here , Ajax .