PL/SQL procedures same row - oracle

Question

Table before solve:
ID NAME DATA
1 zhang 9
1 zhang 12
2 wang 1
2 wang 2
/this is the table before solved/
Table after solve:
ID NAME DATA
1 DIY 13
2 DIY 3
/this is what I want to get result/
There is the procedure:
update A a
set a.date=(select max(f_get(f.id,f.date,g.date))
from A f,A g
where f.date!=g.date
and f.id=a.id);
--function f_get()
create or replace function f_get
(id in varchar2,date in varchar,date2 in varchar )
return varchar is
Result varchar
date3 varchar(4);
begin
select nvl(date,date2) into date3
from dual;
Result:=date3;
delete from A a
where a.ID=id
and a.date=date2;--there is error
return(Result);
end f_get;

Answer 1

Your question does its best to hide itself, but this is the point:
"--there is error "
The error you get is (presumably) ORA-14551: cannot perform a DML operation inside a query, which you are getting because you are calling a FUNCTION which includes a DELETE command from a SELECT statement.
Oracle's transactional model doesn't allow queries to change the state of the database. Instead of a FUNCTION you need to write a procedure.
Although, if you want to remove duplicate rows, a straight SQL solution will suffice. Something like
delete from a
where (id, date) not in
( select id, max(date) from a
group by id)
/

Answer 2

You really should pay attention how to write questions. It would help us to help you. This is my guess what you are looking for. Unfortunately I don't have 9i available, but hope this helps !
create table so7t (
id number,
name varchar2(10),
data number -- date is a reserved word and can't be used as identifier
);
-- 1001
insert into so7t values (1, 'zhang', 9);
-- 1100
insert into so7t values (1, 'zhang', 12);
-- 0001
insert into so7t values (2, 'wang', 1);
-- 0010
insert into so7t values (2, 'wang', 2);
select * from so7t;
/* from http://www.dbsnaps.com/oracle/bitwise-operators-in-oracle/ */
create or replace function bitor (x number, y number)
return number
is
begin
return (x+y)-bitand(x,y);
end;
/
show errors
create or replace procedure solve (
p_id in number
) as
type ids_t is table of number;
v_ids ids_t;
v_result number := 0;
begin
select data bulk collect into v_ids from so7t where id = p_id;
for i in v_ids.first .. v_ids.last loop
v_result := bitor(v_result, v_ids(i));
end loop;
delete from so7t where id = p_id;
insert into so7t values (p_id, 'DIY', v_result);
end;
/
begin
solve(1);
commit;
solve(2);
commit;
end;
/
Table before solve:
ID NAME DATA
---------- ---------- ----------
1 zhang 9
1 zhang 12
2 wang 1
2 wang 2
Table after solve:
ID NAME DATA
---------- ---------- ----------
1 DIY 13
2 DIY 3