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