Oracle -> Mysql Select Problem

I wonder if anyone can help. I am migrating a mysql database to work in oracle.

This is a scaled down query from the whole query I am trying to run

SELECT CLIENT.ID, USERADDRESS.FIRSTNAME AS USER_FIRSTNAME, USERADDRESS.LASTNAME AS USER_LASTNAME
FROM CLIENT
LEFT OUTER JOIN ADDRESS ON ADDRESS.ID = CLIENT.ADDRESS_ID
LEFT OUTER JOIN OPERATOR ON OPERATOR.ID = CLIENT.USER_ID
LEFT OUTER JOIN ADDRESS AS USERADDRESS ON USERADDRESS.ID = OPERATOR.ADDRESS_ID

Mysql will let you use the same table twice in a join by use alias's.

Oracle doesnt seem to like it, is there away around this?

Another problem I have is finding an alternative to the mysql function

unix_timestamp

Thanks

Kev

Have you tried doing the table alias without the "AS":

SELECT CLIENT.ID, USERADDRESS.FIRSTNAME AS USER_FIRSTNAME, USERADDRESS.LASTNAME AS USER_LASTNAME
FROM CLIENT
LEFT OUTER JOIN ADDRESS ON ADDRESS.ID = CLIENT.ADDRESS_ID
LEFT OUTER JOIN OPERATOR ON OPERATOR.ID = CLIENT.USER_ID
LEFT OUTER JOIN ADDRESS USERADDRESS ON USERADDRESS.ID = OPERATOR.ADDRESS_ID

Just a guess :)

Cheers