Sql Coding Help

Question

Hello All,
I need help on getting the sql code.
Here is how the example data is laid out in my data table called example.
name     age     favorite colors
john doe     15     red:blue:green
Notice how the data is in column "favorite colors" they are set values selected from a multiple list.
I need the sql to get it to display like this.
name     age     favorite colors
john doe     15     red
john doe     15     blue
john doe     15     green
thanks

Answer 1

>
Here is how the example data is laid out in my data table called example.
name age favorite colors
john doe 15 red:blue:green
Notice how the data is in column "favorite colors" they are set values selected from a multiple list.
I need the sql to get it to display like this.
name age favorite colors
john doe 15 red
john doe 15 blue
john doe 15 green
>
Storing data in a denormalized form like this usually leads to trouble. Rather than getting into complex programmatic solutions simply to retrieve data, why not use a properly normalized data model that eliminates the problem?
SQL> create sequence subject_seq;
Sequence created.
SQL> create sequence color_seq;
Sequence created.
SQL> create table subjects (
  2        subject_id    integer          primary key
  3    , subject_name  varchar2(30)  not null
  4    , age            number(3, 0)  not null);
Table created.
SQL> create table colors (
  2        color_id    integer        primary key
  3    , color_name  varchar2(20)  not null,
  4    constraint color_name_uk unique (color_name));
Table created.
SQL> create table favorite_colors (
  2        subject_id  integer   not null references subjects
  3    , color_id    integer   not null references colors,
  4    constraint fav_color_pk primary key (
  5          subject_id
  6        , color_id))
  7  organization index;
Table created.
SQL> create index fav_color_ix2 on favorite_colors (
  2        color_id
  3    , subject_id);
Index created.Deal with complexity&mdash;like processing multi-value select lists&mdash;in the bits of the application that lend themselves to it: PL/SQL processes; DB packages etc, using features like the aforementioned <tt>apex_util.string_to_table</tt>:
SQL> declare
  2 
  3    l_sub_id     subjects.subject_id%type;
  4 
  5    procedure process_fav_colors (
  6          p_subject_id  in subjects.subject_id%type
  7        , p_colors_str  in varchar2)
  8    is
  9 
10        l_fav_colors  apex_application_global.vc_arr2;
11 
12    begin
13 
14        l_fav_colors := apex_util.string_to_table(p_colors_str);
15 
16        delete favorite_colors
17        where subject_id = p_subject_id;
18 
19        forall i in l_fav_colors.first()..l_fav_colors.last()
20          insert into favorite_colors
21            (subject_id, color_id)
22          select
23                 p_subject_id
24               , col.color_id
25          from
26                 colors col
27          where
28                 col.color_name = l_fav_colors(i);
29 
30    end process_fav_colors;
31 
32  begin
33 
34    insert into colors values (color_seq.nextval, 'red');
35    insert into colors values (color_seq.nextval, 'green');
36    insert into colors values (color_seq.nextval, 'blue');
37    insert into colors values (color_seq.nextval, 'rose');
38    insert into colors values (color_seq.nextval, 'black');
39    insert into colors values (color_seq.nextval, 'white');
40 
41    insert into subjects
42        (subject_id, subject_name, age)
43    values
44        (subject_seq.nextval, 'john doe', 15)
45    returning
46        subject_id into l_sub_id;
47 
48    process_fav_colors(l_sub_id, 'red:green:blue');
49 
50    insert into subjects
51        (subject_id, subject_name, age)
52    values
53        (subject_seq.nextval, 'man ray', 86)
54    returning
55        subject_id into l_sub_id;
56 
57    process_fav_colors(l_sub_id, 'black:white');
58 
59    insert into subjects
60        (subject_id, subject_name, age)
61    values
62        (subject_seq.nextval, 'pablo picasso', 91)
63    returning
64        subject_id into l_sub_id;
65 
66    process_fav_colors(l_sub_id, 'blue:rose');
67 
68  end;
69  /
PL/SQL procedure successfully completed.Then getting the data in the required form is trivial:
SQL> select
  2              sub.subject_name
  3            , sub.age
  4            , col.color_name
  5  from
  6              subjects sub
  7            , favorite_colors fc
  8            , colors col
  9  where
10              sub.subject_id = fc.subject_id
11  and       fc.color_id = col.color_id
12  order by
13              sub.subject_name
14            , col.color_name;
SUBJECT_NAME                     AGE COLOR_NAME
john doe                      15 blue
john doe                      15 green
john doe                      15 red
man ray                       86 black
man ray                       86 white
pablo picasso                      91 blue
pablo picasso                      91 roseAnd what if there's a requirement to query and analyze the data? Answer questions like: Who likes blue? Or How many subjects have more than 2 favorite colors?
SQL> select
  2              sub.subject_name
  3  from
  4              subjects sub
  5            , favorite_colors fc
  6            , colors col
  7  where
  8              sub.subject_id = fc.subject_id
  9  and       fc.color_id = col.color_id
10  and       col.color_name = 'blue';
SUBJECT_NAME
john doe
pablo picasso
SQL> select
  2              count(*)
  3  from
  4              (select
  5                  count(*)
  6              from
  7                  subjects sub
  8                   , favorite_colors fc
  9                   , colors col
10              where
11                  sub.subject_id = fc.subject_id
12              and      fc.color_id = col.color_id
13              group by
14                  sub.subject_id
15                   , sub.subject_name
16              having
17                  count(*) > 2);
  COUNT(*)
      1This is impossible to do simply and efficiently with the original model.