T-SQL 按条件分组数据

Question

我有一些数据：

时期 | id_account | float_value
24217 | 303003 | 0
24218 | 303003 | 0
24219 | 303003 | 1
24220 | 303003 | 1
24221 | 303003 | 0
24222 | 303003 | 0

我需要像这样对这些数据进行分组：

begin_period | end_period| id_account | float_value     
24217       | 24218     | 303003    |   0   
24219       | 24220     | 303003    |   1   
24221       | 24222     | 303003    |   0

我尝试了 row_number 分区和 while 循环，但没有成功。

Answer 1

我将此理解为 gaps-and-isald 问题，您希望将“相邻”行分组在一起，即具有相同 float_value 的行，跨越具有相同 id_account 和parameter.

这里，我认为最简单的方法是使用行号之间的差异来计算每条记录属于哪个组：

select
    min(period) begin_period,
    max(period) end_period,
    id_account,
    parameter,
    float_value
from (
    select 
        t.*,
        row_number() over(partition by id_account, parameter order by period) rn1,
        row_number() over(partition by id_account, parameter, float_value order by period) rn2
    from mytable t
) t
group by id_account, parameter, float_value, rn1 -rn2
order by id_account, parameter, begin_period

Demo on DB Fiddle:

begin_period | end_period | id_account | parameter      | float_value
-----------: | ---------: | ---------: | :------------- | ----------:
       24217 |      24218 |     303003 | ACCOUNT_STATUS |           0
       24219 |      24220 |     303003 | ACCOUNT_STATUS |           1
       24221 |      24222 |     303003 | ACCOUNT_STATUS |           0

Answer 2

这是一个间隙和孤岛问题，一种方法是使用行数差异法：

WITH cte AS (
    SELECT *, ROW_NUMBER() OVER (PARTITION BY ID_Account ORDER BY Period) rn1,
        ROW_NUMBER() OVER (PARTITION BY ID_Account, Float_Value ORDER BY Period) rn2
    FROM yourTable
)

SELECT
    MIN(Period) AS Begin_Period,
    MAX(Period) AS End_Period,
    ID_Account,
    MAX(Parameter) AS Parameter,   -- assuming Parameter just always has the same value
    Float_Value
FROM cte
GROUP BY
    ID_Account,
    Float_Value,
    rn1 - rn2
ORDER BY
    MIN(Period);

Demo

Answer 3

您可以按如下方式使用row_number。这是 demo.

with cte as
(
  select
     *,
     rn - row_number() over(order by Float_Value, rn) as nrnk
  from
  (
    select
      *,
      row_number() over (order by Period) as rn
    from Table1
  ) subq
)

select
  min(Period) as Begin_Period,
  max(Period) as End_Period,
  ID_Account,
  Parameter,
  Float_Value
from cte
group by
  ID_Account,
  Parameter,
  Float_Value,
  nrnk

输出：

 Begin_Period   End_Period     ID_Account     Parameter   Float_Value
---------------------------------------------------------------------
 24217            24218          303003    ACCOUNT_STATUS   0
 24221            24222          303003    ACCOUNT_STATUS   0
 24219            24220          303003    ACCOUNT_STATUS   1

T-SQL 按条件分组数据

T-SQL grouping data with condition

sql

sql-server

select

window-functions

gaps-and-islands

Demo