Concatena valori da più colonne in Oracle

SQL Fiddle

Impostazione dello schema Oracle 11g R2 :

CREATE TABLE test (col1, col2, col3, col4, col5 ) AS
          SELECT 1, 'A', 'B', 'C', 'D' FROM DUAL
UNION ALL SELECT 2, 'A', 'B', 'C', NULL FROM DUAL
UNION ALL SELECT 3, 'C', 'A', NULL, NULL FROM DUAL
UNION ALL SELECT 4, 'D', 'A', 'C', NULL FROM DUAL
UNION ALL SELECT 5, NULL, NULL, NULL, NULL FROM DUAL
UNION ALL SELECT 6, NULL, NULL, NULL, 'A' FROM DUAL
UNION ALL SELECT 7, 'B', NULL, NULL, 'A' FROM DUAL
UNION ALL SELECT 8, NULL, 'C', NULL, 'A' FROM DUAL;

Query 1 :

Se non ci sono NULL valori tra altri valori (introdurrà più virgole nelle righe 7 e 8):

SELECT col1,
       TRIM( ',' FROM col2||','||col3||','||col4||','||col5 ) AS col2
FROM   test

Risultati :

| COL1 |    COL2 |
|------|---------|
|    1 | A,B,C,D |
|    2 |   A,B,C |
|    3 |     C,A |
|    4 |   D,A,C |
|    5 |  (null) |
|    6 |       A |
|    7 |   B,,,A |
|    8 |    C,,A |

Le ultime due query funzioneranno per tutti gli esempi:

Query 2 :

SELECT col1,
       TRIM( ',' FROM col2 || NVL2( col3, ','||col3, NULL ) || NVL2( col4, ','||col4, NULL ) || NVL2( col5, ','||col5, NULL ) ) AS col2
FROM   test

Risultati :

| COL1 |    COL2 |
|------|---------|
|    1 | A,B,C,D |
|    2 |   A,B,C |
|    3 |     C,A |
|    4 |   D,A,C |
|    5 |  (null) |
|    6 |       A |
|    7 |     B,A |
|    8 |     C,A |

Query 3 :

SELECT col1,
       REGEXP_REPLACE( col2||','||col3||','||col4||','||col5, '(^|,),+|,+($)', '\1' ) AS col2
FROM   test

Risultati :

| COL1 |    COL2 |
|------|---------|
|    1 | A,B,C,D |
|    2 |   A,B,C |
|    3 |    C,A, |
|    4 |   D,A,C |
|    5 |  (null) |
|    6 |       A |
|    7 |     B,A |
|    8 |     C,A |