CASE WHEN statement IS NULL THEN ......

Question

-- i've table's acoount and owner
create table account
( code-number(30) , name-nvarchar(200)) 
create table owner
( code-nvarchar2(20 BYTE) ,
name -nvarchar(100),
account_code-number(30))  account_code is foreign key
code
name
account_code
1.1
a
1.1
5
x
5
3.3
c
3.3
7
y
19
dd
code
name
1.1
z
5
b
3.3
c
3.3
c
now my result should be
code(owner)
name(owner)
code(account)
name(account)
1.1
a
1.1
z
5
x
5.
b
3.3
c
3.3
c
7
y
19
dd
my script
SELECT CASE WHEN O.ACCOUNT_CODE IS NULL THEN A.CODE=NULL  ELSE A.CODE=(VALUE) END,  // HOW SHOULD I WRTIE HERE ???
             CASE WHEN O.ACCOUNT_CODE IS NULL THEN  A.NAME=NULL  ELSE A.NAME=(VALUE) END,
         O.CODE,
         O.NAME
    FROM OWNER  O,
              ACCOUNT  A
   WHERE     A.CODE = O.ACCOUNT_CODE;

Answer 1

I don't see the need for case statement here. Cant you just do this.
SQL> with owner
  2  as
  3  (
  4  select 1.1 code, 'a ' name, 1.1  account_code from dual union all
  5  select 5   code, 'x ' name, 5    account_code from dual union all
  6  select 3.3 code, 'c ' name, 3.3  account_code from dual union all
  7  select 7   code, 'y ' name, null account_code from dual union all
  8  select 19  code, 'dd' name, null account_code from dual
  9  ), account
10  as
11  (
12  select 1.1 code, 'z' name from dual union all
13  select 5   code, 'b' name from dual union all
14  select 3.3 code, 'c' name from dual union all
15  select 3.3 code, 'c' name from dual
16  )
17  select o.code "code (owner)"
18       , o.name "name (owner)"
19       , a.code "code (account)"
20       , a.name "name (account)"
21    from owner o
22    left
23    join (
24           select distinct code, name
25             from account
26         ) a
27      on o.account_code = a.code
28   order
29      by 1;
code (owner) name (owner)    code (account) name (account)
         1.1 a                          1.1 z
         3.3 c                          3.3 c
           5 x                            5 b
           7 y
          19 dd