oracle函数listagg()
发布时间：2020-12-12 15:55:28 所属栏目：百科 来源：网络整理
导读：在开始演示之前我们需要新建一张表出来： 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'
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在开始演示之前我们需要新建一张表出来：
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
)
接着我们可以使用listagg函数来进行演示：
select nation,listagg(city,',') within GROUP (order by city)
from temp
group by nation ;
效果如下： 最基础的用法如下： LISTAGG(XXX,XXX) WITHIN GROUP( ORDER BY XXX) 它的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。 同样是聚合函数，还有一个高级用法 over(partition by XXX)，在不使用Group by语句时候，也可以使用LISTAGG函数，为了进一步演示，我们对原先的表稍加改造： with temp as( select 500 population,'China' nation,'Guangzhou' city from dual union all select 1500 population,'Shanghai' city from dual union all select 500 population,'Beijing' city from dual union all select 1000 population,'USA' nation,'New York' city from dual union all select 500 population,'Bostom' city from dual union all select 500 population,'Japan' nation,'Tokyo' city from dual ) listagg() + over()用法的演示： select population, nation, city, listagg(city,') within GROUP (order by city) over (partition by nation) rank from temp PS：在listagg(city,'/')这里我们可以使用我们想要的分隔符。 （编辑：李大同） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |