Vertica SQL中的Concat GROUP BY

Question

我需要以逗号分隔的id列表作为凌乱的第三方api的字段:s这是我想要实现的简化版本.

| id | name |
|====|======|
| 01 | greg |
| 02 | paul |
| 03 | greg |
| 04 | greg |
| 05 | paul |

SELECT name, {some concentration function} AS ids
FROM table
GROUP BY name

返回

| name | ids        |
|======|============|
| greg | 01, 03, 04 |
| paul | 02, 05     |

我知道MySQL有CONCAT_GROUP函数,我希望在没有安装更多函数的情况下解决这个问题,因为环境.也许我可以使用OVER语句解决这个问题？

Answer 1

你将不得不使用OVER()与NVL()(你将不得不延长串联每名超过10个实例):

CREATE TABLE t1 (
  id int,
  name varchar(10)
);

INSERT INTO t1
SELECT 1 AS id, 'greg' AS name
UNION ALL
SELECT 2, 'paul'
UNION ALL
SELECT 3, 'greg'
UNION ALL
SELECT 4, 'greg'
UNION ALL
SELECT 5, 'paul';

COMMIT;

SELECT name,
    MAX(DECODE(row_number, 1, a.id)) ||
    NVL(MAX(DECODE(row_number, 2, ',' || a.id)), '') ||
    NVL(MAX(DECODE(row_number, 3, ',' || a.id)), '') ||
    NVL(MAX(DECODE(row_number, 4, ',' || a.id)), '') ||
    NVL(MAX(DECODE(row_number, 5, ',' || a.id)), '') ||
    NVL(MAX(DECODE(row_number, 6, ',' || a.id)), '') ||
    NVL(MAX(DECODE(row_number, 7, ',' || a.id)), '') ||
    NVL(MAX(DECODE(row_number, 8, ',' || a.id)), '') ||
    NVL(MAX(DECODE(row_number, 9, ',' || a.id)), '') ||
    NVL(MAX(DECODE(row_number, 10, ',' || a.id)), '') id
FROM
    (SELECT name, id, ROW_NUMBER() OVER(PARTITION BY name ORDER BY id) row_number FROM t1) a
GROUP BY a.name
ORDER BY a.name;

结果

 name |  id
------+-------
 greg | 1,3,4
 paul | 2,5

Answer 2

一个非常老的问题，但作为更新，您可以使用 listagg() 函数

ID	姓名
01	格雷格
02	保罗
03	格雷格
04	格雷格
05	保罗

SELECT name, listagg(id) AS ids FROM 表 GROUP BY 名称

这将返回期望的输出：

姓名	id
格雷格	01, 03, 04
保罗	02, 05