PL/SQL - Select columns values as string array

Question

I am not sure if this question is asked anywhere else before. I am not sure how to put it also. But I will explain with a scenario.
I have the following tables
TAB1 with columns : USERID, CODE, COUNTRY
TAB2 with columns : USERID, CODE, EMAIL

Example contents:

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

TAB2:
RISHI, A1B2C3, rishi1@test.com
RISHI, A1B2C3, rishi2@test.com
RISHI, A1B2C3, rishi3@test.com
RISHI, D2E3F4, rishi1@test.com
RISHI, D2E3F4, rishi2@test.com
KANTA, G3H4I5, kanta1@test.com

What I want from a select query or pl/sql stored procedure is a result like this:

RISHI, INDIA, A1B2C3, (rishi1@test.com, rishi2@test.com, rishi3@test.com)
RISHI, INDIA, D2E3F4, (rishi1@test.com, rishi2@test.com)

If I do a select like :

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';

I get the result as :

RISHI, INDIA, A1B2C3, rishi1@test.com
RISHI, INDIA, A1B2C3, rishi2@test.com
RISHI, INDIA, A1B2C3, rishi3@test.com
RISHI, INDIA, D2E3F4, rishi1@test.com
RISHI, INDIA, D2E3F4, rishi2@test.com

What I basically need is the email ids grouped together into an array. Assume that TAB1 contains many more columns which I actually require but I have omitted in this example, but TAB2 has only these three columns.

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

I think you want to use the GROUP_CONCAT aggregate function in MySQL. The bad news is Oracle don't have a built-in function for group concactenation and the good news is you can emulated such functionality like that.

Look at this snippet:

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

and will return

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

REFERENCE