Oracle 一行拆分为多行

测试数据：

1. CREATE TABLE t (str VARCHAR2(30));
2. INSERT INTO t VALUES ( 'X,Y,Z' );
3. INSERT INTO t VALUES ( 'XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG' );
4. commit;

--1、multiset 8i之后都支持

1. SQL> CREATE OR REPLACE TYPE number_ntt AS TABLE OF NUMBER;
2. 2  /
3. Type created
4. SQL> col value for a20
5. SQL>
6. SQL> with ilv as
7. 2   (select str || ',' as str,
8. 3           (length(str) - length(replace(str, ','))) + 1 as no_of_elements
9. 4      from t)
10. 5  select a.str, regexp_substr(a.str, '[^,]+', 1, b.column_value) value
11. 6    from ilv a, table(cast(multiset (select rownum rn
12. 7                       from dual
13. 8                     connect by rownum <= a.no_of_elements) as number_ntt)) b;
14. STR                             VALUE
15. ------------------------------- --------------------
16. X,Y,Z,                          X
17. X,Y,Z,                          Y
18. X,Y,Z,                          Z
19. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG, XXX
20. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG, Y
21. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG, ZZ
22. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG, AAAAA
23. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG, B
24. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG, CCC
25. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG, D
26. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG, E
27. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG, F
28. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG, GGG
29. 13 rows selected
30. SQL>

2、自关联connect by 10g之后

1. SQL> select str,
2. 2         regexp_substr(str, '[^,]+', 1, level) value
3. 3    from t
4. 4  connect by
5. 5   str = prior str
6. 6   and instr(str||',', ',', 1, level) > 0
7. 7   and prior dbms_random.value is not null;
8. STR                            VALUE
9. ------------------------------ --------------------
10. X,Y,Z                          X
11. X,Y,Z                          Y
12. X,Y,Z                          Z
13. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG XXX
14. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG Y
15. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG ZZ
16. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG AAAAA
17. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG B
18. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG CCC
19. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG D
20. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG E
21. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG F
22. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG GGG
23. 13 rows selected
24. SQL>

3、自关联，非CONNECT BY方式

1. SQL> with tmp as (
2. 2  select t.*,
3. 3         length(str)-length(regexp_replace(str, ',', ''))+1 len
4. 4    from t
5. 5  )
6. 6  select a.*, regexp_substr(str, '[^,]+', 1, rn) value
7. 7    from tmp a, (select rownum rn from dual connect by level <= (select max(len) from tmp x)) b
8. 8   where a.len>=b.rn
9. 9   order by 1;
10. STR                                   LEN VALUE
11. ------------------------------ ---------- --------------------
12. X,Y,Z                                   3 Y
13. X,Y,Z                                   3 Z
14. X,Y,Z                                   3 X
15. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG         10 GGG
16. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG         10 B
17. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG         10 CCC
18. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG         10 D
19. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG         10 E
20. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG         10 F
21. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG         10 ZZ
22. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG         10 Y
23. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG         10 XXX
24. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG         10 AAAAA
25. 13 rows selected
26. SQL>

4、Model子句，复杂度有点小高

1. SQL> col single_element for a15
2. SQL>
3. SQL> with ilv as
4. 2   (select str as orig_str,
5. 3           ',' || str || ',' as mod_str,
6. 4           1 as start_pos,
7. 5           length(str) as end_pos,
8. 6           (length(str) - length(replace(str, ','))) + 1 as element_count,
9. 7           0 as element_no,
10. 8           rownum as rn
11. 9      from t)
12. 10  select orig_str as original_string,
13. 11         substr(mod_str, start_pos, end_pos - start_pos) as single_element,
14. 12         element_no,
15. 13         element_count
16. 14    from (select *
17. 15            from ilv
18. 16           model partition by(rn, orig_str, mod_str)
19. 17                 dimension by(element_no)
20. 18                 measures(start_pos, end_pos, element_count)
21. 19                 rules iterate(2000)
22. 20                    until(iteration_number + 1 = element_count[0])(
23. 21                        start_pos[iteration_number + 1] = instr(cv(mod_str), ',', 1, cv(element_no)) + 1,
24. 22                        end_pos[iteration_number + 1] = instr(cv(mod_str), ',', 1, cv(element_no) + 1)
25. 23                    )
26. 24          )
27. 25   where element_no != 0
28. 26   order by mod_str, element_no;
29. ORIGINAL_STRING                SINGLE_ELEMENT  ELEMENT_NO ELEMENT_COUNT
30. ------------------------------ --------------- ---------- -------------
31. X,Y,Z                          X                        1
32. X,Y,Z                          Y                        2
33. X,Y,Z                          Z                        3
34. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG XXX                      1
35. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG Y                        2
36. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG ZZ                       3
37. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG AAAAA                    4
38. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG B                        5
39. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG CCC                      6
40. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG D                        7
41. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG E                        8
42. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG F                        9
43. XXX,Y,ZZ,AAAAA,B,CCC,D,E,F,GGG GGG                     10
44. 13 rows selected
45. SQL>

其他可以编写自定义函数进行拆分