構建測試表：
sql**
create
table table1
(
id integer,
name varchar2(10)
)
create
table table2
(
id integer,
role varchar2(10)
)
insert
into table1 (id, name) values (1, '張三');
insert
into table1 (id, name) values (2, '李四');
commit;
insert
into table2 (id, role) values (1, '查詢');
insert
into table2 (id, role) values (1, '分析');
insert
into table2 (id, role) values (1, '決策');
insert
into table2 (id, role) values (2, '查詢');
commit;
create table table1
(id integer,
name varchar2(10)
)create table table2
(id integer,
role varchar2(10)
)insert into table1 (id, name) values (1, '張三');
insert into table1 (id, name) values (2, '李四');
commit;
insert into table2 (id, role) values (1, '查詢');
insert into table2 (id, role) values (1, '分析');
insert into table2 (id, role) values (1, '決策');
insert into table2 (id, role) values (2, '查詢');
commit;
sql**
id name role
1 張三 查詢,分析,決策
2 李四 查詢
id name role
1 張三 查詢,分析,決策
2 李四 查詢
一、使用wmsys.wm_concat
sql**
select table1.*,wmsys.wm_concat(role) from table1,table2 where table1.id=table2.id
group
by table1.id,table1.name
select table1.*,wmsys.wm_concat(role) from table1,table2 where table1.id=table2.id
group by table1.id,table1.name
二、使用sys_connect_by_path
sql**
select id, name, ltrim(max(sys_connect_by_path(role, ',')), ',') from
(select row_number() over(partition by table1.id order
byname) rn,table1.*, role from table1, table2 where table1.id =
table2.id)
start with rn = 1
connect
byprior rn = rn - 1 and
prior id = id
group
by id, name
order
by id
select id, name, ltrim(max(sys_connect_by_path(role, ',')), ',') from
(select row_number() over(partition by table1.id order by name) rn,table1.*, role from table1, table2 where table1.id =
table2.id)
start with rn = 1
connect by prior rn = rn - 1 and prior id = id
group by id, name
order by id
三、使用自定義函式
sql**
create
orreplace
function my_concat(mid in
integer) return varchar2 --記住：引數和返回值裡的資料型別都不用定義長度
isresult varchar2(4000); --定義變數，記住oracle中定義變數不需要
begin
for temp_cursor in (select role from table2 where id=mid) loop --此處在游標for迴圈中使用查詢
result :=result || temp_cursor.role || ','; --oracle中字元連線使用||，而sql server中用+
end loop;
result := rtrim(result,','); --去掉最後乙個空格,還有oracle中的賦值前面沒有set
return result;
end;
select table1.*,my_concat(table1.id) from table1,table2 where table1.id=table2.id
group
by table1.id,table1.name
order
by table1.id
原文：
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