该语法在Oracle中无效。你可以这样做：

UPDATE table1 SET table1.value = (SELECT table2.CODE

FROM table2

WHERE table1.value = table2.DESC)

WHERE table1.UPDATETYPE='blah'

AND EXISTS (SELECT table2.CODE

FROM table2

WHERE table1.value = table2.DESC);

或者你可以这样做：

UPDATE

(SELECT table1.value as OLD, table2.CODE as NEW

FROM table1

INNER JOIN table2

ON table1.value = table2.DESC

WHERE table1.UPDATETYPE='blah'

) t

SET t.OLD = t.NEW

(这取决于内联视图是否被Oracle视为可更新)。