aggregate function to concatenate strings in Vertica

Question

have a table in vertica: test like this:

ID     |   name
1      |    AA
2      |    AB
2      |    AC
3      |    AD
3      |    AE
3      |    AF
         


        

Answer 1

SELECT id,
    MAX(DECODE(row_number, 1, a.name)) ||
    NVL(MAX(DECODE(row_number, 2, ',' || a.name)), '') ||
    NVL(MAX(DECODE(row_number, 3, ',' || a.name)), '') ||
    NVL(MAX(DECODE(row_number, 4, ',' || a.name)), '') ||
    NVL(MAX(DECODE(row_number, 5, ',' || a.name)), '') ||
    NVL(MAX(DECODE(row_number, 6, ',' || a.name)), '') ||
    NVL(MAX(DECODE(row_number, 7, ',' || a.name)), '') ||
    NVL(MAX(DECODE(row_number, 8, ',' || a.name)), '') ||
    NVL(MAX(DECODE(row_number, 9, ',' || a.name)), '') ||
    NVL(MAX(DECODE(row_number, 10, ',' || a.name)), '')||
    NVL(MAX(DECODE(row_number, 11, ',' || a.name)), '') ||
    NVL(MAX(DECODE(row_number, 12, ',' || a.name)), '') ag
FROM
    (SELECT id, name, ROW_NUMBER() OVER(PARTITION BY name ORDER BY id) row_number FROM test) a
GROUP BY a.id
ORDER BY a.id;