CREATE TABLE fnd_user_bck AS
SELECT * FROM fnd_user_tab;

-- No guarantees regarding uniqueness
UPDATE fnd_user_tab fut
  SET web_user = ( SELECT UPPER(value)
                   FROM fnd_user_property_tab fupt
                   WHERE fupt.identity = fut.identity
                   AND fupt.name = 'SMTP_MAIL_ADDRESS'
                   AND value IS NOT NULL )
WHERE EXISTS ( SELECT 1
               FROM fnd_user_property_tab fupt
               WHERE fupt.identity = fut.identity
               AND fupt.name = 'SMTP_MAIL_ADDRESS'
               AND value IS NOT NULL )
AND identity NOT IN ('IFSADMIN','IFSWEBCONFIG','IFSCONNECT','IFSPLSQLAP','IFSPRINT','IFSMOBILITY','IFSMONITORING')