does this suit you?

use strict;

my @tablenums = ('1', '2', '3');

my %tables =
(
    '1' => { name => "john",  data => [] },
    '2' => { name => "mike",  data => [] },
    '3' => { name => "harry", data => [] },
);

foreach (@tablenums)
{
    push @{$tables{$_}->{data}}, "any", "data", "goes", "here";
}

print "$tables{1}->{name}`s data is @{$tables{1}->{data}}!";
#prints "john`s data is any data goes here!"
[download]

Update: If you insist using dedicated arrays (which is bad style) you could use this code:

use strict;

my @tablenums = ('1', '2', '3');
my (@johnData, @mikeData, @harryData);

my %tables =
(
    '1' => { name => "john",  data=>\@johnData },
    '2' => { name => "mike",  data=>\@mikeData },
    '3' => { name => "harry", data=>\@harryData },
);

foreach (@tablenums)
{
    push @{$tables{$_}->{data}}, "any", "data", "goes", "here";
}

print "john`s data is @johnData!";
#prints "john`s data is any data goes here!"
[download]

see perlref and perlreftut