### Table 1
    $sth = $dbh->prepare("select * from master_table_1");

while (@row=$sth->fetchrow) {
$query = "insert into back_table_2 (f1,f2,f3) VALUES ('@row[0]','@row[1]','@row[2]')"

}

### Table 2
### Table 1
    $sth = $dbh->prepare("select * from master_table_2");

while (@row=$sth->fetchrow) {
$query = "insert into back_table_2 (abc1,abc2,abc3) VALUES ('@row[0]','@row[1]','@row[2]')"

}