按列值分区的小计

Question

如果我有以下数据：

match '/', to: 'blog_posts#index', constraints: { subdomain: 'blog' }, via: [:get, :post, :put, :patch, :delete]

我按K1＆amp; amp;分区我的数据K2，所以我可以得到总计数：

K1   K2  V3 
100  A   C
100  A   C
100  A   D
200  B   D
200  B   D
200  B   C

哪个收益率：

count(V3) over (partition by K1, K2)

如何获取引用行中值的分区的小计？结果将是：

K1   K2  V3  Total 
100  A   C   3
100  A   C   3
100  A   D   3
200  B   D   2
200  B   E   2

Answer 1

 SELECT 
      K1,
      K2,
      V3, 
      count(V3) over (partition by K1, K2) as Total,
      count(V3) over (partition by K1, K2, V3) as Subtotal
FROM DataTable