UPDATE ITRN_HIS
SET    USER_ALPHA3 = SUBSTR(RPAD(USER_ALPHA3, 15, ' '), 1, 15) || 'Y' || SUBSTR(USER_ALPHA3, 17)
WHERE  SOURCE = 5
       AND SOURCE_QUAL = 5
       AND CCN = 'PASDL'
       AND MAS_LOC = 'PRO'
       AND USER_ALPHA3 <> ' '
       AND NVL(SUBSTR(USER_ALPHA3, 16, 1), ' ') <> 'Y'
       AND
       (POSTING_DATE BETWEEN TO_DATE('20080101', 'YYYYMMDD') AND TO_DATE('20080131', 'YYYYMMDD'))
       AND
       USER_ALPHA3 IN
       (SELECT SUBSTR(C_SOQMD_INVOICE, 1, 15) FROM C_SOQMD WHERE TRIM(C_SOQMD_INVOICE) <> 'LAST')
       AND EXISTS (SELECT *
        FROM   C_SOQID
        WHERE  INVOICE = SUBSTR(ITRN_HIS.USER_ALPHA3, 1, 15)
               AND SO = ITRN_HIS.REF
               AND SO_LINE = ITRN_HIS.REF_LINE)