$sql1 = “select * from table1”;
$sql2 = “select * from table2”;

my $table1= $dbh->selectall_hashref($sql1, "primary_key");
my $table2= $dbh->selectall_hashref($sql2, "primary_key");

foreach (keys(%$table1)) {
 $table1_foreign_key = 
  $table2->{$table1->{$_}{foreign_key}}{primary_key};
}

##</code><code>##

foreach $tbl1_primary (keys(%$table1)) {
 foreach (keys(%$table3)) {
  while ( $table3->{$_}{$table1->{$tbl1_primary}{foreign_key}} == 
$table3->{$_}{foreign_key} ) {
  $table1_foreign_key_table3 = 
   $table3->{$_}{$table1->{$tbl1_primary}{foreign_key}};
  }
 }
}

##</code><code>##

$sql_obfuscate = qq {
SELECT *
FROM clinvest.dbf a,
     clinvpmt.dbf b,
     clinvchg.dbf c,
	 ernames.dbf d,
	 ercontct.dbf e
WHERE a.CID = b.INVESTID
and a.CID = c.INVESTID
and a.NAMEID = d.NAMEID
and a.NAMEID = e.NAMEID
};