How to split comma-separated values into multiple rows in Oracle table - sql

Question

SELECT year, movietitle, director, actorname
FROM films11
WHERE actorname like '%Christina Ricci%'
order by year asc;
produces the following in ORACLE SQL Developer from the original data schema.
I want to transform the whole table so that the primary key becomes the actor name. (like in the second table)
This way the query
SELECT year, movietitle, director, actorname
FROM films11
WHERE actorname like '%Christina Ricci%'
order by year asc;
will produce only the searched item (either create a new view, or change the data schema completely.) (third table)

Answer 1

Step 1 : "How to blow up a database"
From :
SQL Fiddle
Oracle 11g R2 Schema Setup:
Query 1:
select * from films11
Results:
| YEAR | DIRECTOR | MOVIETITLE | ACTORNAME |
|------|----------|------------|----------------|
| 2000 | dir1 | title1 | act1,act2 |
| 2001 | dir2 | title2 | act1,act2,act3 |
| 2002 | dir1 | title3 | act4 |
Query 2:
select YT.year, YT.movietitle,
REPLACE(REGEXP_SUBSTR(YT.actorname||',','.*?,',1,lvl.lvl),',','') AS actorname
from films11 YT
join (select level as lvl
from dual
connect by level <= (select max(regexp_count(actorname,',')+1) from films11)
) lvl on lvl.lvl <= regexp_count(YT.actorname,',')+1
order by YT.year, YT.movietitle, actorname
With a nice Cartesian product :
Results:
| YEAR | MOVIETITLE | ACTORNAME |
|------|------------|-----------|
| 2000 | title1 | act1 |
| 2000 | title1 | act2 |
| 2001 | title2 | act1 |
| 2001 | title2 | act2 |
| 2001 | title2 | act3 |
| 2002 | title3 | act4 |
You run it ONCE and use it to move everything to a normalized DB
Here is the full script to change your schema to something more convenient...
CREATE TABLE actors(
id_actor NUMBER GENERATED BY DEFAULT ON NULL AS IDENTITY,
act_name VARCHAR2(100)
)
;
CREATE TABLE directors(
id_director NUMBER GENERATED BY DEFAULT ON NULL AS IDENTITY,
dir_name VARCHAR2(100)
)
;
CREATE TABLE movies(
id_movie NUMBER GENERATED BY DEFAULT ON NULL AS IDENTITY,
mov_year NUMBER,
mov_name VARCHAR2(100),
director_id NUMBER
)
;
CREATE TABLE playedby(
movie_id NUMBER,
actor_id NUMBER
)
;
INSERT INTO directors (dir_name)
SELECT DISTINCT director dir_name
FROM films11
;
INSERT INTO movies (mov_year, mov_name, director_id)
SELECT year mov_year, movietitle mov_name, directors.id_director director_id
FROM films11
INNER JOIN directors ON directors.dir_name = films11.director
;
INSERT INTO actors (act_name)
SELECT DISTINCT t.actorname act_name
FROM (
SELECT YT.year, YT.movietitle,
REPLACE(REGEXP_SUBSTR(YT.actorname||',','.*?,',1,lvl.lvl),',','') AS actorname
FROM films11 YT
JOIN (SELECT level AS lvl
FROM dual
CONNECT BY level <= (SELECT MAX(REGEXP_COUNT(actorname,',')+1) FROM films11)
) lvl ON lvl.lvl <= REGEXP_COUNT(YT.actorname,',')+1
) t
;
INSERT INTO playedby (movie_id, actor_id)
SELECT movies.id_movie movie_id, actors.id_actor actor_id
FROM (
SELECT YT.year, YT.movietitle,
REPLACE(REGEXP_SUBSTR(YT.actorname||',','.*?,',1,lvl.lvl),',','') AS actorname
FROM films11 YT
JOIN (SELECT level AS lvl
FROM dual
CONNECT BY level <= (SELECT MAX(REGEXP_COUNT(actorname,',')+1) FROM films11)
) lvl ON lvl.lvl <= REGEXP_COUNT(YT.actorname,',')+1
) t
INNER JOIN actors ON t.actorname = actors.act_name
INNER JOIN movies ON t.year = movies.mov_year AND t.movietitle = movies.mov_name
;
After that you can just make a select like that :
Query 3:
SELECT mov_year, mov_name, dir_name, act_name
FROM movies
INNER JOIN directors ON directors.id_director = movies.director_id
INNER JOIN playedby ON movies.id_movie = playedby.movie_id
INNER JOIN actors ON playedby.actor_id = actors.id_actor
WHERE act_name like '%act2%'
order by mov_year asc
Results:
| MOV_YEAR | MOV_NAME | DIR_NAME | ACT_NAME |
|----------|----------|----------|----------|
| 2000 | title1 | dir1 | act2 |
| 2001 | title2 | dir2 | act2 |