早期 - 枢轴 table

Question

嗨，我有一个 table 这样的：

Session id  Property
1           Radar
2           Bullet
1           Bullet
3           Radar
2           Price

我想转换成这样：

Radar   Bullet   Price
  1       1
          2        2
  3

Answer 1

对于固定的属性列表，您可以进行条件聚合：

select session_id,
    max(case when property = 'Radar'  then 1 else 0 end) as radar,
    max(case when property = 'Bullet' then 1 else 0 end) as bullet,
    max(case when property = 'Price'  then 1 else 0 end) as price
from mytable
group by session_id

这会将会话 ID 放在第一列中，并将 0/1 值放在每列中，具体取决于给定会话是否拥有给定的属性.

要生成您显示的准确输出（这可能不如上面的有用），您可以这样做：

select 
    case when max(case when property = 'Radar'  then 1 else 0 end) = 1 then session_id end as radar,
    case when max(case when property = 'Bullet' then 1 else 0 end) = 1 then session_id end as bullet,
    case when max(case when property = 'Price'  then 1 else 0 end) = 1 then session_id end as price 
from mytable
group by session_id

早期 - 枢轴 table

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