gamiensrule:

Assuming last_name is the column you want to sort on, you should be able to use:

my $clients = $get->fetchall_hashref('id');
my @list = keys %$clients;
my @sorted_list = sort { $$clients{$a}{last_name} cmp $$clients{$b}{la
+st_name} }
                       @list;
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Remember to replace cmp with <=> for numeric fields.

...roboticus

When your only tool is a hammer, all problems look like your thumb.

Update: After re-reading OP, I replaced SORT_KEY with last_name, to match his problem statement.