sub getTableStructure {
	# need: $dbh
	#		tablename
	# returns: hash of field(column) records

	my ($dbh, $tablename) = @_;
	my %struct_hash;
	my $SQL = "SHOW COLUMNS FROM $tablename";
	my $sth = $dbh->prepare( $SQL );
	$sth->execute();
	while ( my $inphash = $sth->fetchrow_hashref() ) {
		$struct_hash{$inphash->{Field}} = $inphash->{Type};
	}
	return %struct_hash;
}