java - 如何将不同列的值分组到一行中？

Question

我有一个如下所示的源表:

如何使结果表看起来像这样。我可以在 sql 或 java 代码中使用解决方案。

拜托，谁能帮帮我。 谢谢。

Answer 1

我认为最简单的方法是同时应用 UNPIVOT 和 PIVOT 函数来获得结果:

select account, description,
  [value_1], [value_2], [value_3], [value_4]
from
(
  select account, description, col, value,
    row_number() over(partition by account, col order by col) rn
  from 
  (
    select [account], [description], [value_1], [value_2], [value_3], [value_4]
    from yourtable
  ) src
  unpivot
  (
    value 
    for col in ([value_1], [value_2], [value_3], [value_4])
  ) un
) s
pivot
(
  max(value)
  for col in ([value_1], [value_2], [value_3], [value_4])
) piv

参见 SQL Fiddle with Demo .

这也可以使用 UNION ALL 作为 unpivot 和聚合函数以及 CASE 表达式来完成:

select account, description,
  max(case when col = 'value_1' then value end) value_1,
  max(case when col = 'value_2' then value end) value_2,
  max(case when col = 'value_3' then value end) value_3,
  max(case when col = 'value_4' then value end) value_4
from
(
  select account, description, col, value,
    row_number() over(partition by account, col order by account) rn
  from
  (
    select [account], [description], 'value_1' col, [value_1] value 
    from yourtable
    where [value_1] is not null
    union all
    select [account], [description], 'value_2' col, [value_2] value 
    from yourtable
    where [value_2] is not null
    union all
    select [account], [description], 'value_3' col, [value_3] value 
    from yourtable
    where [value_3] is not null
    union all
    select [account], [description], 'value_4' col, [value_4] value 
    from yourtable
    where [value_4] is not null
  ) s
) un
group by account, description, rn

参见 SQL Fiddle with Demo

两者都给出结果:

| ACCOUNT |  DESCRIPTION |  VALUE_1 |  VALUE_2 |  VALUE_3 |  VALUE_4 |
----------------------------------------------------------------------
|  A00005 | Account Desc | ABCD0081 | BCDE0010 | BKCP0010 | SMTP0010 |
|  A00005 | Account Desc | ABCD0082 |   (null) | BKCP0011 |   (null) |