oracle行转列函数

构建测试表：
create table TABLE1  

(   
  ID   INTEGER,   
  NAME VARCHAR2(10)   
)   
  
create table TABLE2   
(   
  ID   INTEGER,   
  ROLE VARCHAR2(10)   
)   
  
insert into TABLE1 (ID, NAME) values (1, '张三');   
insert into TABLE1 (ID, NAME) values (2, '李四');   
commit;   
  
insert into TABLE2 (ID, ROLE) values (1, '查询');   
insert into TABLE2 (ID, ROLE) values (1, '分析');   
insert into TABLE2 (ID, ROLE) values (1, '决策');   
insert into TABLE2 (ID, ROLE) values (2, '查询');   
commit;  
要求输出结果：
ID  NAME    ROLE   
1    张三 查询,分析,决策   
2    李四 查询 
     
 

方法一、使用wmsys.wm_concat

select table1.*,wmsys.wm_concat(role) from table1,table2 where table1.id=table2.id  

group by table1.id,table1.name 

 

方法二、使用sys_connect_by_path

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

 

方法三、使用自定义函数

create or replace function my_concat(mid in integer) return varchar2  

--记住：参数和返回值里的数据类型都不用定义长度   
is  
result varchar2(4000);    --定义变量，记住Oracle中定义变量不需要   
begin  
       for temp_cursor in (select role from table2 where id=mid) loop    

       --此处在游标FOR循环中使用查询   
           result :=result || temp_cursor.role || ',';   

           --Oracle中字符连接使用||，而sql server中用+          
       end loop;   
       result := rtrim(result,','); 

       --去掉最后一个空格,还有Oracle中的赋值前面没有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

以上是转载网上网友的，只有发现还有一个方式：

先看示例代码：

with temp as(
  select 'China' nation ,'Guangzhou' city from dual union all
  select 'China' nation ,'Shanghai' city from dual union all
  select 'China' nation ,'Beijing' city from dual union all
  select 'USA' nation ,'New York' city from dual union all
  select 'USA' nation ,'Bostom' city from dual union all
  select 'Japan' nation ,'Tokyo' city from dual
)
select nation,listagg(city,',') within GROUP (order by city)
from temp
group by nation

with temp as(
  select 'China' nation ,'Guangzhou' city from dual union all
  select 'China' nation ,'Shanghai' city from dual union all
  select 'China' nation ,'Beijing' city from dual union all
  select 'USA' nation ,'New York' city from dual union all
  select 'USA' nation ,'Bostom' city from dual union all
  select 'Japan' nation ,'Tokyo' city from dual 
)
select nation,listagg(city,',') within GROUP (order by city)
from temp
group by nation

 这是最基础的用法：

LISTAGG(XXX,XXX) WITHIN GROUP( ORDER BY XXX)

 

用法就像聚合函数一样，通过Group by语句，把每个Group的一个字段，拼接起来。

非常方便。

 

同样是聚合函数，还有一个高级用法：

就是over(partition by XXX)

也就是说，在你不实用Group by语句时候，也可以使用LISTAGG函数：

with temp as(
  select 500 population, 'China' nation ,'Guangzhou' city from dual union all
  select 1500 population, 'China' nation ,'Shanghai' city from dual union all
  select 500 population, 'China' nation ,'Beijing' city from dual union all
  select 1000 population, 'USA' nation ,'New York' city from dual union all
  select 500 population, 'USA' nation ,'Bostom' city from dual union all
  select 500 population, 'Japan' nation ,'Tokyo' city from dual
)
select population,
       nation,
       city,
       listagg(city,',') within GROUP (order by city) over (partition by nation) rank
from temp

with temp as(
  select 500 population, 'China' nation ,'Guangzhou' city from dual union all
  select 1500 population, 'China' nation ,'Shanghai' city from dual union all
  select 500 population, 'China' nation ,'Beijing' city from dual union all
  select 1000 population, 'USA' nation ,'New York' city from dual union all
  select 500 population, 'USA' nation ,'Bostom' city from dual union all
  select 500 population, 'Japan' nation ,'Tokyo' city from dual 
)
select population,
       nation,
       city,
       listagg(city,',') within GROUP (order by city) over (partition by nation) rank
from temp

 

总结：LISTAGG()把它当作SUM()函数来使用就可以了。