oracle wm_concat 列转行 逗号分隔

create table wlbtest1( 
username varchar2(2), 
deptID number 
); 
create table wlbtest2( 
deptName varchar2(10), 
deptID number 
); 
insert into wlbtest1 values ('a', 1); 
insert into wlbtest1 values ('b', 1); 
insert into wlbtest1 values ('c', 1); 
insert into wlbtest1 values ('d', 2); 
insert into wlbtest1 values ('e', 2); 
insert into wlbtest1 values ('f', 2); 
insert into wlbtest2 values ( '部门1' ,1); 
insert into wlbtest2 values ( '部门2', 2); 
select deptID, wm_concat(username) username,'部门'||deptID deptName from wlbtest1 group by deptID