请高手帮忙写下sql语句
有2张表，表结构如下  
表名meetinginfo  
meetingid   varchar   50   主键     (会议ID)  
meetingname   varchar   50           (会议名)  
createrid   varchar   50               (发起人ID)  
joinid   varchar   50                     (参与者ID)  

表名userinfo  
userid   varchar   50   主键           (用户ID)  
username   varchar   50                 (用户名)  

表meetinginfo中数据如下  
"m1 "   "ParmentMeeting "   "vk001 "   "vk002,vk003 "  
"m2 "   "GloabMeeting "   "CEO001 "   "vk001,tk001 "  

表userinfo中数据如下  
"CEO001 "   "张三 "  
"vk001 "   "李四 "  
"vk002 "   "王五 "  
"vk003 "   "钱六 "  
"tk001 "   "许七 "  

现在要实现以下结果：  
"m1 "   "ParmentMeeting "   "李四 "   "王五,钱六 "  

我想了好久，不知道怎么写，请高手帮忙  


------解决方案--------------------
select a.meetingid, meetingname, b.username, c.usernames
from meetinginfo a , userinfo b, ( select c1.userid|| ', '||c2.userid userids, c1.username|| ', '||c2.username usernames from userinfo c1, userinfo c2) c
where a.createrid = b.userid
and a.joinid = c.userids
------解决方案--------------------
临时写的:
SQL> select * from meetinginfo;

MEETINGID MEETINGNAM CREATERID JOINID
-------------------- ---------- ---------- ------------------------------
m1 PM vk001 vk002,vk003
m2 GM CE001 vk001,tk001

SQL> select meetingid,meetingname,f_h(joinid) aa from meetinginfo;

MEETINGID MEETINGNAM AA
-------------------- ---------- ------------------------------
m1 PM 王五,钱六
m2 GM 李四,许七


create or replace function f_h(arg_res in varchar2) return varchar2
is
namelist varchar2(1100);
sss varchar2(30);
i number;
j number;
aa varchar2(1000);
begin
i:=0;
j:=1;
aa:=arg_res|| ', ';

loop
j:= instr(aa, ', ',i+1);
EXIT WHEN j=0;
sss := substr(aa,i+1,j-i-1);
select username into sss from userinfo where userid=sss;
namelist :=namelist|| ', '||sss;
i:=j;
end loop;
namelist:=substr(namelist,-(length(namelist)-1));
return(namelist);
end f_h;

------解决方案--------------------

String sql = "select * from meetinginfo ";
ResultSet rs=st.executeQuery(sql);
ArrayList al = new ArrayList();
while (rs.next())
{
MeetinginfoBean mbean = new MeetinginfoBean();
String joinid =rs.getString( "joinid ");
mbean.set(rs.getString( "joinid ");
.............
al.add(mbean);
)
rs.close();
for(int i=0;i <al.size();i++){
MeetinginfoBean mbean = (MeetinginfoBean)al.get(i);
Str