如何修复单行子查询在选择查询中返回多行问题以便以所需的方式获得结果？

Question

源表

Cost Category	Cost Category Type	Q1-2020	Q2-2020	Q3-2020	Q4-2020
Employee Impacted	Period Cost	10	20	0	4000

想要的结果

Cost Category	Cost Category Type	Quarter Year	Value
Employee Impacted	Period Cost	Q1-2020	10
Employee Impacted	Period Cost	Q2-2020	20
Employee Impacted	Period Cost	Q3-2020	0
Employee Impacted	Period Cost	Q4-2020	4000

我正在尝试使用以下查询

SELECT 'Q'|| LEVEL ||'-2020' AS id,
       REGEXP_SUBSTR((select ATTRIBUTE_34 || ',' || ATTRIBUTE_35 || ',' ||
                            ATTRIBUTE_36 || ',' || ATTRIBUTE_37
                       from view_form_539766),
                     '[^,]+',
                     1,
                     LEVEL) AS data
  FROM dual
CONNECT BY REGEXP_SUBSTR((select ATTRIBUTE_34 || ',' || ATTRIBUTE_35 || ',' ||
                                ATTRIBUTE_36 || ',' || ATTRIBUTE_37
                           from view_form_539766),
                         '[^,]+',
                         1,
                         LEVEL) IS NOT NULL

Answer 1

你可以把它写成联合查询：

Select CostCategory, CostCategoryType, 'Q1-2020' as QuarterYear, Q1-2020 as Value
from table1
union all
Select CostCategory, CostCategoryType, 'Q2-2020' as QuarterYear, Q2-2020 as Value
from table1
union all
.....

Answer 2

您可以使用为此类任务开发的unpivot：

with a (
  Cost_Category,
  Cost_Category_Type,
  Q1_2020,
  Q2_2020,
  Q3_2020,
  Q4_2020
) as (
  select
    'Employee Impacted',
    'Period Cost',
    10,
    20,
    0,
    4000
  from dual
)
select *
from a
unpivot (
  value
  for Quarter_Year in (
    q1_2020 as 'Q1-2020',
    q2_2020 as 'Q2-2020',
    q3_2020 as 'Q3-2020',
    q4_2020 as 'Q4-2020'
  )
)

成本类别 | COST_CATEGORY_TYPE | QUARTER_YEAR |价值 :---------------- | :----------------- | :----------- | ----: 员工受影响 |期间费用 | 2020 年第一季度 | 10 员工受影响 |期间费用 | 2020 年第二季度 | 20 员工受影响 |期间费用 | 2020 年第三季度 | 0 员工受影响 |期间费用 | 2020 年第四季度 | 4000

db小提琴here