PCMS_CHDOC_DATA.CH_DOC_ID     PCMS_ITEM_DATA.LIB_FILENAME
                                          1                                                             A.TXT
                                          1                                                             B.TXT
                                          1                                                             C.TXT
                                          2                                                            PROVA.PDF

Vorrei avere:
                      PCMS_CHDOC_DATA.CH_DOC_ID     PCMS_ITEM_DATA.LIB_FILENAME
                                            1                                                A.TXT, B.TXT, C.TXT
                                            2                                                          PROVA.PDF