Question

I have Table with values

X     Y     Z  
-     ---   - 
1     abc   P
1     def   Q

I need a normal query (not pl/sql) which can give result as

X  Y        Z
-  -------  ---
1  abc,def  P,Q

i.e Based on column X the values are converted into csv format

There can be more than three columns.

Answer 1

You can choose any one of the following techniques to aggregate your strings

On occasion it is necessary to aggregate data from a number of rows
into a single row, giving a list of data associated with a specific
value. Using the SCOTT.EMP table as an example, we might want to
retrieve a list of employees for each department. Below is a list of
the base data and the type of output we would like to return from an
aggregate query.

Base Data:

    DEPTNO ENAME
---------- ----------
        20 SMITH
        30 ALLEN
        30 WARD
        20 JONES
        30 MARTIN
        30 BLAKE
        10 CLARK
        20 SCOTT
        10 KING
        30 TURNER
        20 ADAMS
        30 JAMES
        20 FORD
        10 MILLER

Desired Output:

    DEPTNO EMPLOYEES
---------- --------------------------------------------------
        10 CLARK,KING,MILLER
        20 SMITH,FORD,ADAMS,SCOTT,JONES
        30 ALLEN,BLAKE,MARTIN,TURNER,JAMES,WARD

Personally, I find this syntax very readable

SELECT x, wm_concat(y), wm_concat(z) 
FROM   xyz
GROUP BY x;