sql - 将列转换为行值的表转置

Question

我有下表：

id      purch_d7   purch_d30     
 1         10             25
 2          5             15

我想把它转置/转成这种格式

 id     purchase_count   purch_window
  1           10         purch_d7
  1           25         purch_d30 
  2            5         purch_d7
  2           15         purch_d30

我将如何在 Vertica 中执行此操作？此外，如果想要将输出旋转/转置回原始视图，我该怎么做？

Answer 1

你可以尝试使用UNION ALL

SELECT id,purch_d7 as purchase_count,'purch_d7' as purch_window FROM T
UNION ALL 
SELECT id,purch_d30,'purch_d30' FROM T

Answer 2

我喜欢让代码显示我正在尝试做的事情。我将命名列垂直旋转到值和“值名称”。所以我在我提供的附加表中添加值名称。

开始：

WITH
-- don't add this first one to your query - it's just your data ...
input(id,purch_d07,purch_d30) AS (
          SELECT  1,10,25
UNION ALL SELECT  2, 5,15
)
,
-- real WITH clause starts here ...
-- add the possible purch types as an in-line table with labels
purch_window(purch_window) AS (
          SELECT 'purch_d07'
UNION ALL SELECT 'purch_d30'
)
SELECT 
  id
, CASE purch_window 
    WHEN 'purch_d07' THEN purch_d07
    WHEN 'purch_d30' THEN purch_d30
  ELSE NULL
  END AS purchase_count
, purch_window
FROM input CROSS JOIN purch_window
ORDER BY 1,3
;

然后转身：...

WITH
input(id,purch_d07,purch_d30) AS (
          SELECT  1,10,25
UNION ALL SELECT  2, 5,15
)
,
-- real WITH clause starts here ...
-- add the possible purch types as an in-line table with labels
purch_window(purch_window) AS (
          SELECT 'purch_d07'
UNION ALL SELECT 'purch_d30'
)
,
pivoted AS (
SELECT 
  id
, CASE purch_window 
    WHEN 'purch_d07' THEN purch_d07
    WHEN 'purch_d30' THEN purch_d30
  ELSE NULL
  END AS purchase_count
, purch_window
FROM input CROSS JOIN purch_window
)
SELECT
  id
, SUM(CASE purch_window WHEN 'purch_d07' THEN purchase_count END) AS purch_d07
, SUM(CASE purch_window WHEN 'purch_d30' THEN purchase_count END) AS purch_d30
FROM pivoted
GROUP BY 1
ORDER BY 1
;

您所要做的就是将其复制粘贴到您的 vsql 客户端（或您用来连接到 Vertica 的任何客户端......）