Using DECODE Function to change data

Question

I am trying to use the Decode function in a SQL statement to find a field that has a specific type, and when it finds that type, I want to blank out the results in a different field.
For example:
DECODE(ADDR_TYPE,'HOME',PHONE='') HOME_PHONE

Answer 1

something like:
SQL> with t as
  2   (select 219 id,
  3           'BUS' addr_type,
  4           '505-555-5555' phone
  5      from dual
  6    union
  7    select 219 id,
  8           'HOME' addr_type,
  9           null   phone
10      from dual
11    union
12    select 220 id,
13           'BUS' addr_type,
14           '101-111-1111'   phone
15      from dual
16    union
17    select 220 id,
18           'HOME' addr_type,
19           null   phone
20      from dual
21    union
22    select 223 id,
23           'BUS' addr_type,
24           '202-222-2222'   phone
25      from dual
26    union
27    select 224 id,
28           'HOME' addr_type,
29           '303-333-3333'   phone
30      from dual
31    union
32    select 225 id,
33           'BUS' addr_type,
34           null   phone
35      from dual
36    union
37    select 226 id,
38           'HOME' addr_type,
39           null   phone
40      from dual)
41  select a.id,
42         a.addr_type,
43         decode(a.addr_type,'BUS',phone,null) phone
44    from (select id, addr_type, phone,
45                 row_number() over (partition by id order by id, decode(addr_type,'BUS',1,2)) rn
46            from t) a
47   where a.rn = 1;
        ID ADDR PHONE
       219 BUS  505-555-5555
       220 BUS  101-111-1111
       223 BUS  202-222-2222
       224 HOME
       225 BUS
       226 HOME
6 rows selected.
SQL>