DevOps, CI/CD and Automation

Hello,

I have a following query

Select '||' || RW."Description" || ':' || RW."Reason_Code"
from TMTABLE UL, XMLTABLE('//Row' PASSING UL.TEXT
COLUMNS
"Event" CHAR(10) PATH 'Event',
"Reason_Code" PATH 'Reason_Code',
"Description" PATH 'Description'
) AS RW
WHERE
UL.ID = '[Param.1]' and
UL.QUEUENAME = '[Param.2]' and
RW."Event" = '[Param.3]'

which returns me following result set

||A:00052
||B:00053
||C:00054
||D:00055
||E:00056

But I want all these rows to be concatenated like this : A:00052||B:00053||C:00054||D:00055||E:00056

So I had written following query:

Select substr( (Select '||' || RW."Description" || ':' || RW."Reason_Code"
from TMTABLEUL, XMLTABLE('//Row' PASSING UL.TEXT
COLUMNS
"Event" CHAR(10) PATH 'Event',
"Reason_Code" PATH 'Reason_Code',
"Description" PATH 'Description'
) AS RW
WHERE
UL.ID = '[Param.1]' and
UL.QUEUENAME = '[Param.2]' and
RW."Event" = '[Param.3]' ) , 3 , 2000 ) from Dual

But it gives this error: java.sql.SQLException: ORA-01427: single-row subquery returns more than one row

what should I do to achieve desired result?