Ok, según el violín que me diste, probé estos y funcionó para mí
create table account( account_id number primary key,
account_status varchar2(30));
insert into account values(1, '5');
insert into account values(2, '3');
insert into account values(3, '2');
select * from account
update account
set account_status= case
when account_id=1 then '2'
when account_id=2 then '5'
when account_id=3 then '3'
END
select * from account
No usé la condición where
