…
my $sth = $dbh->prepare("show tables") or &bail($DBI::errstr);
my $rv = $sth->execute or &bail($DBI::errstr);
while ( ( my $table_name ) = $sth->fetchrow_array ) {
  $sth2 = $dbh->prepare("describe $table_name") or die print "Can't do select: $DBI::errstr";
  $rv2 = $sth2->execute or die print "Can't execute the query: $DBI::errstr";
  while (($field_, $type_, $null_,$key_, $default_, $extra_) = $sth2->fetchrow_array) {
	#stuff with cols and then rows.
  }
}
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