It's easier to do this in SQL and not in Perl.

You need to do an outer join between the two tables.

select t1.name, t2.name
from t1
left outer join t2
on t1.name = t2.name
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You'll get back a two column result set. If a name is in both tables then it will appear in both columns. If it only appears in t1 then the second column will contain NULL.

You then need to write the Perl that handles that and creates your list.

A good solution, but it assumes that table 2 is a subset of table 1. This may be true, but is not explicitly said, So if in the above example table 2 also contained 'brian', then 'brian' would be missing from the output. The addition of a union would fill in any rows in table 2 but not in table 1

select t1.name, t2.name 
from t1
left outer join t2 on t1.name = t2.name
union
select t2.name, t1.name
from t2
left outer join t1 on t2.name = t1.name
where isnull(t1.name)
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select 
    table1.name as left_name,
    table2.name as right_name
from
    table1
left join
    table2
on
    table1.name=table2.name
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I suggest you read up on relational databases, foreign keys, natural vs. synthetic keys etc. Your model smells of denormalisation.

my @table1 = GetNames( 'Table1');
my @table2 = GetNames( 'Table2');
my %names = ();
map {$names{$_}++} (@table1, @table2);
while (my ($name, $weight) =  each %names) {
  if ( $weight > 1 ) {
    PrintBoldly($name);
  } else {
    PrintNormally($name);
  }
}
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