Sql 按常用名称划分行对

假设我有一个presto语句返回

|Name|Type    |Count|
|A   | total  |   2 |
|A   | count  |   4 |
|B   | total  |   3 |
|B   | count  |   9 |

我怎样才能达到这样的目标

|Name|Avg |
|A   |  2 |
|B   |  3 |

基本上

A.avg = A.count/A.total
B.avg = B.count/B.total

谢谢

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PS：不是说你精通SQL，你可以用自连接的方式来实现

select a.Name, 
Total/Count as Avg 
from (select Name, Count as total From tbl where Type = 'total')a
inner join (select Name, Count From tbl where Type = 'count') b on a.Name = b.Name

---

我会简单地使用条件加成：

select name,
       ( max(case when type = 'count' then count end) /
         max(case when type = 'total' then count end)
       ) as average
from t
group by name;

实际上，如果我们假设

total

=

count

，那么这就更简单了：

select name, min(count) / max(count) as average
from t
group by name;

如果您确实更喜欢

加入
而不是
分组方式
：

select t.name, tc.count / tt.count
from t tc join
     t tt
     on tc.name = tt.name and
        tc.type = 'count' and
        tt.type = 'total';

@尼奥。这比必要的要复杂得多。