前言
- 本文对 PostgreSQL 14.x 适用
- 实现的方式是用
unnest将
表 jounal 结构示例
id author
2 [张三, 李四, 王五]
2 [张三, 李四]
3 [张三]聚合结果
item cnt
张三 3
李四 2
王五 1
sql 语句
sql 语句写法一
select item, count(item) as cnt
from (select unnest(journal.author) as item from journal) as tmp
group by itemsql 语句写法二
select item, count(distinct id) as cnt
from journal, unnest(journal.author) as item
group by itemsql 语句写法三
select item, count(item) as cnt
from journal, unnest(journal.author) as item
group by item相关链接
- How to group result by array column in Postgres?
- Group by unique items in an array column and count records that contain each item
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