To store the actual PDF in the database you could use a field of BLOB type (Binary Large OBject) or possibly CLOB (Character Large OBject). Depending on type you would either have to read the contents of the file into a variable of MEMPTR or LONGCHAR type and then store it in the database.
To view it you could for instance temporarily store the PDF on disk again and then open it using Arobe Reader.
The Progress Knowledgebase (knowledgebase.progress.com) has a good example in Solution no 20873. I cannot seem to link directly to it though.