use DBI qw( :sql_types );
...
my $types = $sth->{TYPE};
foreach my $type ( @{ $types } ) {
  print "VARCHAR"  if ( $type == SQL_VARCHAR );
  print "DATETIME" if ( $type == SQL_DATETIME );
  print "BOOLEAN"  if ( $type == SQL_BIT );
  print "FLOAT"    if ( $type == SQL_FLOAT );
  ...
}