#table1
fruit_id   fruit
1          apple
2          orange
3          pear

#table2
some_id fruit_id  some_col
1       1         a1
2       1         a2
3       1         a3
4       2         z1
5       2         z2

my $dbi = get_connection();

# sql
my $sql = q~
SELECT fruit, some_col
FROM table1
LEFT JOIN table2
   ON table1.fruit_id=table2.fruit_id
WHERE table1.fruit_id=1
~;

# Relevent Perl code
my $sth = $dbh->prepare($sql);
$sth->execute();
my $matrix_ref = $sth->fetchall_arrayref();

##</code><code>##

[[apple, a1], [apple, a2], [apple, a3]]; 

##</code><code>##

[[apple, a1, a2, a3]];