what is oracle update statement with inner join ?

Answer

UPDATE table1 SET table1.value =(SELECT table2.CODE
                                  FROM table2 
                                  WHERE table1.value = table2.DESC)WHERE table1.UPDATETYPE='blah'ANDEXISTS(SELECT table2.CODE
            FROM table2 
            WHERE table1.value = table2.DESC);

Or you might be able to do this:

UPDATE(SELECT table1.value as OLD, table2.CODE as NEW
 FROM table1
 INNERJOIN table2
 ON table1.value = table2.DESCWHERE table1.UPDATETYPE='blah') t
SET t.OLD = t.NEW