SELECT * FROM v$version ;

BANNER                                                          
----------------------------------------------------------------
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bi
PL/SQL Release 10.2.0.4.0 - Production                          
CORE	10.2.0.4.0	Production                                      
TNS for Solaris: Version 10.2.0.4.0 - Production                
NLSRTL Version 10.2.0.4.0 - Production                          

5 rows selected.

SET LINE 150
COLUMN PRINT_NAME FORMAT A20
COLUMN PATH FORMAT A80
SET ECHO ON

SQL> select print_name FROM tqits20_tfm_sec_user
     WHERE user_id = 16470

PRINT_NAME          
--------------------
Matthews, Markus    

1 row selected.

SQL> --Case 1.
SQL> SELECT     print_name,SYS_CONNECT_BY_PATH (print_name, ',') PATH
      FROM tqits20_tfm_sec_user
     WHERE user_id = 16470
CONNECT BY NOCYCLE PRIOR user_id = manager_id AND LEVEL <= 10

ORA-30004: when using SYS_CONNECT_BY_PATH function, cannot have seperator as part of column value

SQL> -- Case 2
SQL> SELECT     print_name,SYS_CONNECT_BY_PATH (print_name, '~') PATH
      FROM tqits20_tfm_sec_user
     WHERE user_id = 16470
CONNECT BY NOCYCLE PRIOR user_id = manager_id AND LEVEL <= 10

PRINT_NAME           PATH                                                                            
-------------------- --------------------------------------------------------------------------------
Matthews, Markus     ~Matthews, Markus                                                               
Matthews, Markus     ~Morgan, Graham~Matthews, Markus                                                
Matthews, Markus     ~James, Andrew Terrence (Old Users)~Morgan, Graham~Matthews, Markus             

3 rows selected.

ORA-30004: when using SYS_CONNECT_BY_PATH function, cannot have seperator as part of column value
 *Cause:
 *Action: Use another seperator which does not occur in any column value,
          then retry.