将多行转换为一行

Posted 2023-05-09

【中文标题】将多行转换为一行

【英文标题】：convert multiple rows into one row

【发布时间】：2020-05-04 13:48:46

【问题描述】：

我有这张桌子：

id  operation  phone_number  package
1   Add        991           super_package no. 2    
1   Delete     991           super_package no. 1
2   Add        902           super_package no. 3    
2   Delete     902           super_package no. 1
2   Add        988           super_package no. 5    
2   Delete     988           super_package no. 2

我想查询该表，使其看起来像这样：

id  phone_number  new_pkg              old_pkg
1   991           super_package no. 2  super_package no. 1
2   902           super_package no. 3  super_package no. 1
3   988           super_package no. 5  super_package no. 2

如果操作是add，new_pkg 值设置为package 列的值，如果操作是delete，old_pkg 值设置为package 列的值。

我能做的就是这样：

SELECT id,phone_number  , LISTAGG(package, ', ') WITHIN GROUP (ORDER BY id) AS new_pkg
FROM table GROUP BY id;

结果

id phone_number  new_pkg  
1  991           super_package no. 2, super_package no. 1
2  902           super_package no. 3, super_package no. 1
3  988           super_package no. 5, super_package no. 2

有什么帮助吗？

【问题讨论】：

您的输出中的 id=3 来自哪里？您在输入中是否有错字 - 最后两行的 id=3，而不是 2？

【参考方案1】：

我想你想要条件聚合：

SELECT id, phone_number,
       MAX(CASE WHEN operation = 'ADD' THEN package END) as new_pkg,
       MAX(CASE WHEN operation = 'DELETE' THEN package END) as old_pkg
FROM table
GROUP BY id, phone_number;

【参考方案2】：

你需要的操作叫做pivoting。 Oracle 为此添加了 pivot 运算符，早在 11.1 版本。

with
  sample_data (id, operation, phone_number, package) as (
    select 1, 'Add'   , 991, 'super_package no. 2' from dual union all    
    select 1, 'Delete', 991, 'super_package no. 1' from dual union all
    select 2, 'Add'   , 902, 'super_package no. 3' from dual union all
    select 2, 'Delete', 902, 'super_package no. 1' from dual union all
    select 3, 'Add'   , 988, 'super_package no. 5' from dual union all
    select 3, 'Delete', 988, 'super_package no. 2' from dual
  )
-- End of sample data (for testing only, not part of the query).
-- Use your real table name in the FROM clause below.
select id, phone_number, new_pkg, old_pkg
from   sample_data
pivot  (min(package) for operation in ('Add' as new_pkg, 'Delete' as old_pkg))
order  by id  --  if needed
;

ID  PHONE_NUMBER  NEW_PKG              OLD_PKG            
--  ------------  -------------------  -------------------
 1           991  super_package no. 2  super_package no. 1
 2           902  super_package no. 3  super_package no. 1
 3           988  super_package no. 5  super_package no. 2

【讨论】：

效果很好：dbfiddle here