You have to use LEFT JOIN in order to upadte all records in the v_AgendaPhar. With INNER JOIN the records in v_AgendaPhar that don't have matching records in derived table pd will not be updated.

  UPDATE v_AgendaPhar  ;
      SET nstkjour = NVL( pd.nStkjourCor , 0 ) +1 ;
    FROM v_AgendaPhar;
      LEFT JOIN(;
        SELECT apd.nstkjour AS nStkjourCor , apd.itraiterId ;
          FROM  AgendaPhar apd ;
          WHERE apd.iagendadateid < vp_id ) pd ;
    ON v_AgendaPhar.itraiterId = pd.itraiterId

>
>I have many problems to know the stock of previous days.
>I want for the day ( iagendadateid = 2 ) the stock of ( iagendadateid = 1 ) + 1
>
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