I tried to replicate your observation using oracle 8.1.3 with perl 5.5.3 and perl 5.8.0 on a solaris 8 system. The 5.5.3 (with DBI.pm version 1.15 and DBD.pm revision 10.8) worked as hoped for: a table field that ends with a space can be retrieved using a statement with a "?" placeholder, and passing a string with final space as a parameter to the statement's "execute" method.

The 5.8.0 version (DBI version 1.4, DBD revision 11.8) behaved like your case -- same table, same data, same methods. I didn't get a chance to step into the "execute" call with the debugger. Nor was I able to test a more recent perl version.

I was able to confirm that the placehold worked when the parameter value was "Smith_" and the query condition was "where lastname like ?" -- so it's almost certainly a matter of losing trailing white-space from the parameter value within the execute call.