Oracle 列转行函数 Listagg()示例

构建测试数据

 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   )  --将对应城市拼成行形式select nation,listagg(city,',') within GROUP (order by city)  from temp  group by nation --若需要加'',则如下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