SQL & PL/SQL

Hi,
below my stored procedure:

CREATE OR REPLACE PROCEDURE MY_PROC IS
ERR_NUM                          NUMBER;
ERR_MSG                          VARCHAR2(300);
V_COUNT                          NUMBER;
V_EM_ID                          VARCHAR2(64);
V_EM_NUMBER                      VARCHAR2(64);
V_NAME_FIRST                     VARCHAR2(64);
V_EMAIL                          VARCHAR2(64);
V_CELLULAR_NUMBER                VARCHAR2(64);
V_STATUS                         VARCHAR2(64);
V_HONORIFIC                      VARCHAR2(64);
V_EMSTD                          VARCHAR2(64);
V_DP_ID                          VARCHAR2(64);
V_PCT_RM                         NUMBER;
V_DATA_CESSAZIONE                DATE;
 
 
      CURSOR A IS
      SELECT A.MATRICOLA, A.CID_RIFERIMENTO, A.NOME, A.COGNOME, A.MAILBOX, A.DESC_QUALIFICA,
      A.STATO, A.SESSO, DECODE (TRIM(A.DESC_QUALIFICA), 'Dirigente','DIR','Consulente',
                                      'CONSUL','Quadro','QUADRO','Operaio','OPERAIO',
                                'Impiegato', DECODE(TRIM(A.LIVELLO),'4','IMP_QUARTO',
                                '5','IMP_QUINTO','6','IMP_SESTO','7','IMP_SETTIMO','IMP_NOLIVELLO' ),'NA') QUALIFICA_LIVELLO,
      A.CODICE, A.PCTPARTTIME, A.DATA_CESSAZIONE
      FROM WA_TO_AFM A
      WHERE STATO='1';
 
BEGIN
      FOR CUR_A IN A
    LOOP
        BEGIN
 
               IF  CUR_A.CID_RIFERIMENTO  IS NULL     THEN
 
                       SELECT COUNT(*)
                       INTO V_COUNT
                       FROM EM_BK B
                       WHERE B.EM_NUMBER=CUR_A.MATRICOLA;
 
                       IF V_COUNT = 0 THEN
 
                                    INSERT INTO EM_BK (EM_ID, EM_NUMBER, NAME_FIRST,NAME_LAST, EMAIL ,STATUS, HONORIFIC, CONTINGENCY_EMAIL, DP_ID, PCT_RM, EM_STD, W_DATA_CESSAZIONE)
                                    VALUES (CUR_A.COGNOME||'_'||SUBSTR(CUR_A.NOME,1,3)||SUBSTR(CUR_A.MATRICOLA,-2),
                                    CUR_A.MATRICOLA, CUR_A.NOME,CUR_A.COGNOME, CUR_A.MAILBOX, CUR_A.STATO, CUR_A.SESSO, CUR_A.QUALIFICA_LIVELLO,
                                    CUR_A.CODICE, NVL(CUR_A.PCTPARTTIME,1), DECODE (TRIM(CUR_A.DESC_QUALIFICA), 'Dirigente','DIR',
                                                       'Consulente','CONSUL',
                                                       'Quadro','FUNZ',
                                                       'Operaio','IMP',
                                                       'Impiegato','IMP'), CUR_A.DATA_CESSAZIONE);
                       
                       -- here I'd like to handle EXCEPTION  DUP_VAL_ON_INDEX FOR CUR_A.CID_RIFERIMENTO  IS NULL

                       
                       END IF;
               ELSE     -- CUR_A.CID_RIFERIMENTO IS NOT NULL

                               SELECT COUNT(*)
                               INTO V_COUNT
                               FROM EM_BK
                               WHERE EM_NUMBER=CUR_A.MATRICOLA;
 
                               IF V_COUNT=0 THEN 
                               
                               
                               SELECT EM_ID,EMAIL,STATUS, HONORIFIC,CONTINGENCY_EMAIL, DP_ID, PCT_RM, W_DATA_CESSAZIONE
                                      INTO V_EM_ID,V_EMAIL,V_STATUS, V_HONORIFIC,V_EMSTD, V_DP_ID, V_PCT_RM, V_DATA_CESSAZIONE
                                      FROM EM_BK
                                      WHERE EM_NUMBER=CUR_A.CID_RIFERIMENTO;
                               
                               
                               INSERT INTO EM_BK (EM_ID, EM_NUMBER, NAME_FIRST,NAME_LAST, EMAIL ,STATUS, HONORIFIC,CONTINGENCY_EMAIL, DP_ID, PCT_RM, EM_STD, W_DATA_CESSAZIONE,W_FLAG_CID_RIFERIMENTO)
                                            VALUES (CUR_A.COGNOME||'_'||SUBSTR(CUR_A.NOME,1,3)||SUBSTR(CUR_A.MATRICOLA,-2),
                                            CUR_A.MATRICOLA, CUR_A.NOME,CUR_A.COGNOME, V_EMAIL, V_STATUS,V_HONORIFIC,V_EMSTD, V_DP_ID, V_PCT_RM,
                                            DECODE (TRIM(CUR_A.DESC_QUALIFICA), 'Dirigente','DIR',
                                                       'Consulente','CONSUL',
                                                       'Quadro','FUNZ',
                                                       'Operaio','IMP',
                                                       'Impiegato','IMP'), V_DATA_CESSAZIONE, 'Y');
 

                               END IF;
 
               END IF;
               
               -- here I'd like to handle EXCEPTION  DUP_VAL_ON_INDEX FOR CUR_A.CID_RIFERIMENTO  IS NOT NULL
 
                  EXCEPTION
          
                  WHEN DUP_VAL_ON_INDEX  THEN
                        INSERT INTO EM_BK (EM_ID, EM_NUMBER, NAME_FIRST,NAME_LAST, EMAIL ,STATUS, HONORIFIC,CONTINGENCY_EMAIL, DP_ID, PCT_RM, EM_STD, W_DATA_CESSAZIONE, W_FLAG_CID_RIFERIMENTO)
                                            VALUES (CUR_A.COGNOME||'_'||SUBSTR(CUR_A.NOME,1,3)||SUBSTR(CUR_A.MATRICOLA,-2)||'_'||SUBSTR ('00000' || SEQ_EM_ID.NEXTVAL, -5),
                                            CUR_A.MATRICOLA, CUR_A.NOME,CUR_A.COGNOME, V_EMAIL, V_STATUS,V_HONORIFIC,V_EMSTD, V_DP_ID, V_PCT_RM,
                                            DECODE (TRIM(CUR_A.DESC_QUALIFICA), 'Dirigente','DIR',
                                                       'Consulente','CONSUL',
                                                       'Quadro','FUNZ',
                                                       'Operaio','IMP',
                                                       'Impiegato','IMP'), V_DATA_CESSAZIONE, 'Y');
         END;
    END LOOP;
            COMMIT;
 
END;

I handle EXCEPTION DUP_VAL_ON_INDEX ONLY FOR CUR_A.CID_RIFERIMENTO IS NOT NULL

I'd like to handle EXCEPTION DUP_VAL_ON_INDEX ALSO FOR CUR_A.CID_RIFERIMENTO IS NULL

How can I modify my stored procedure (begin...end...innested)?

Thanks in advance!