create table t1 (Player varchar2(10),score varchar2(10))


insert into t1 values('001','10')


insert into t1 values('001','20')


insert into t1 values('002','20')

insert into t1 values('002','20')

insert into t1 values('001','10')


insert into t1 values('002','10')

insert into t1 values('003','20')

insert into t1 values('002','20')

insert into t1 values('001','10')


select * from t1

drop table t1;
create table t1 (Player varchar2(10),score varchar2(10));
insert into t1 values('001','10');
insert into t1 values('001','20');
insert into t1 values('002','20');
insert into t1 values('002','20');
insert into t1 values('001','10');
insert into t1 values('002','10');
insert into t1 values('003','20');
insert into t1 values('002','20');
insert into t1 values('001','10');
commit;

SQL> with
  2    data as (
  3      select player, score, row_number() over (partition by player order by null) rn
  4      from t1
  5    )
  6  select player,
  7         substr(sys_connect_by_path(score,','),2) scores
  8  from data
  9  where connect_by_isleaf = 1
 10  connect by prior player = player and prior rn = rn - 1
 11  start with rn = 1
 12  /
PLAYER     SCORES
---------- --------------------------------------------------
001        10,20,10,10
002        20,10,20,20
003        20

SQL> CREATE OR REPLACE FUNCTION f2 (p_deptno NUMBER)
  2     RETURN VARCHAR2
  3  IS
  4     a   VARCHAR2 (100);
  5  BEGIN
  6     FOR i IN (SELECT ename
  7                 FROM emp
  8                WHERE deptno = p_deptno)
  9     LOOP
 10        a := a || ',' || i.ename;
 11     END LOOP;
 12     RETURN a;
 13  END;
 14  /

Function created.

SQL> select deptno,f2(deptno) from emp
  2  group by deptno
  3  /

DEPTNO  F2(DEPTNO)
------- ----------------------------------
30      ,BLAKE,ALLEN,WARD,MARTIN,TURNER,JAMES
20      ,JONES,SCOTT,FORD,SMITH,ADAMS
10      ,KING,CLARK,MILLER

Used the same functionality in my Palyer and score..

SQL> CREATE OR REPLACE FUNCTION f4 (p_PLAYER VARCHAR2)
  2     RETURN VARCHAR2
  3  IS
  4     a   VARCHAR2 (100);
  5  BEGIN
  6     FOR i IN (SELECT SCORE
  7                 FROM t1
  8                WHERE PLAYER = p_PLAYER)
  9     LOOP
 10        a := a || ',' || i.SCORE;
 11     END LOOP;
 12     RETURN a;
 13  END;
 14  /

Function created.

SQL> 
SQL> SELECT   player, f4 (player) score
  2      FROM t1
  3  GROUP BY player
  4  ORDER BY player
  5  /

PLAYER   SCORE
-------  ---------------
001      [b],20,10,10[/b]
002      ,20,20,10,20
003      ,20

I need 

Player Score
------ ---------
001   [b] 10,20,10,10[/b]
002    20,20,10,20
003    20

Function f4  output
PLAYER   SCORE
-------  ----------
001      ,20,10,10 --->This!!
002      ,20,20,10,20
003      ,20

Needed out put

Player Score
------ ---------
001    10,20,10,10 --->This!!
002    20,20,10,20
003    20

SQL> SELECT   player, f4 (player) score FROM t1
  2  GROUP BY player
  3  ORDER BY player
  4  /
PLAYER     SCORE
---------- ------------------------------
001        ,10,20,10,10
002        ,20,20,10,20
003        ,20

SQL> CREATE OR REPLACE FUNCTION f4 (p_PLAYER VARCHAR2)
  2     RETURN VARCHAR2
  3  IS
  4     a   VARCHAR2 (100);
  5  BEGIN
  6     FOR i IN (SELECT SCORE
  7                 FROM t1
  8                WHERE PLAYER = p_PLAYER)
  9     LOOP
 10        a := LTRIM(a,',')|| ',' || i.SCORE;
 11     END LOOP;
 12     RETURN a;
 13  END;
 14  /

Function created.

SQL> SELECT   player, f4 (player) score
  2      FROM t1
  3  GROUP BY player
  4  ORDER BY player
  5  /

PLAYER  SCORE
------  --------------
001     20,10,10
002     20,20,10,20
003     ,20       ---->This One!!!!!

(2014-07-30 08:11:54) bla@bodb >select * from t1;

PLAYER     SCORE
---------- ----------------------------------------------------------------------------------------------------
001        10
001        20
002        20
002        20
001        10
002        10
003        20
002        20
001        10

9 rijen zijn geselecteerd.

Verstreken: 00:00:00.06
(2014-07-30 08:11:58) bla@bodb >select player, f4(player) score from t1 group by player order by player;

PLAYER     SCORE
---------- ----------------------------------------------------------------------------------------------------
001        ,10,20,10,10
002        ,20,20,10,20
003        ,20

Verstreken: 00:00:00.03
(2014-07-30 08:12:04) bla@bodb >

CREATE OR REPLACE FUNCTION f4 (p_player VARCHAR2)
   RETURN VARCHAR2
IS
   a   VARCHAR2 (100);
BEGIN
   FOR i IN (SELECT score
               FROM t1
              WHERE player = p_player)
   LOOP
      --a := LTRIM(a,',')|| ',' || i.SCORE;
      IF a IS NULL
      THEN
         a := i.score;
      ELSE
         a := LTRIM (a, ',') || ',' || i.score;
      END IF;
   END LOOP;
   RETURN a;
END;

SELECT   player, f4 (player) score
    FROM t1
GROUP BY player
ORDER BY player