PL/SQL - 选择列值作为字符串数组

Question

我不确定这个问题之前是否在其他地方被问过。我也不知道该怎么说。但我会用一个场景来解释。
我有下表
TAB1 包含列：用户 ID、代码、国家/地区
TAB2 包含列： USERID、CODE、EMAIL

示例内容：

TAB1:
RISHI, A1B2C3, INDIA
RISHI, D2E3F4, INDIA
KANTA, G3H4I5, INDONESIA

TAB2:
RISHI, A1B2C3, [email protected]
RISHI, A1B2C3, [email protected]
RISHI, A1B2C3, [email protected]
RISHI, D2E3F4, [email protected]
RISHI, D2E3F4, [email protected]
KANTA, G3H4I5, [email protected]

我想要从选择查询或 pl/sql 存储过程中得到如下结果：

RISHI, INDIA, A1B2C3, ([email protected], [email protected], [email protected])
RISHI, INDIA, D2E3F4, ([email protected], [email protected])

如果我执行如下选择：

select a.userid, a.code, a.country, b.email
from tab1.a, tab2.b
where a.userid = b.userid
and a.code = b.code
and a.userid = 'RISHI';

我得到的结果为：

RISHI, INDIA, A1B2C3, [email protected]
RISHI, INDIA, A1B2C3, [email protected]
RISHI, INDIA, A1B2C3, [email protected]
RISHI, INDIA, D2E3F4, [email protected]
RISHI, INDIA, D2E3F4, [email protected]

我基本上需要的是电子邮件 ID 组合在一起形成一个数组。假设 TAB1 包含我实际需要的更多列，但我在本示例中省略了，但 TAB2 只有这三列。

Answer 1

select a.userid, a.code, a.country, listagg(b.email, ',') within group (order by b.email) as "Emails"
from tab1.a, tab2.b
where a.userid = b.userid
and a.code = b.code
and a.userid = 'RISHI'
group by a.userid, a.code, a.country;

Answer 2

我想你想在MySQL中使用GROUP_CONCAT聚合函数。坏消息是 Oracle 没有用于组串联的内置函数，好消息是您可以模拟此类功能。

看一下这个片段：

with data
     as
     (
          select job,
                ename,
                row_number() over (partition by job order by ename) rn,
                count(*) over (partition by job) cnt
      from emp
     )
 select job, ltrim(sys_connect_by_path(ename,','),',') scbp
  from data
  where rn = cnt
  start with rn = 1
  connect by prior job = job and prior rn = rn-1
  order by job

并将返回

JOB       SCBP
--------- ----------------------------------------
ANALYST   FORD,SCOTT
CLERK     ADAMS,JAMES,MILLER,SMITH
MANAGER   BLAKE,CLARK,JONES
PRESIDENT KING
SALESMAN  ALLEN,MARTIN,TURNER,WARD

REFERENCE

Answer 3

select  listagg(n,  ', ')  
 within group (order by n) con
  from(select department_id d, first_name || ' ' || last_name n from employee 
            where department_id  = 1) ;

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CON
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Alice Perry, Doris Graham, Doris Powell