在 SQL 服务器中搜索序列模式

Question

我有这样的记录，我想在 SQL 服务器中按模式和序列（如（50,54,50））在值字段中搜索它应该返回 02,03,04 任何人都知道这样做。

======================================
Id             Date             Value
01             2020-01-01       50
02             2020-01-02       50
03             2020-01-03       54
04             2020-01-04       50
05             2020-01-05       35
06             2020-01-06       98
07             2020-01-07       13
======================================

Answer 1

用户语音站点上有一个请求添加对 T-SQL 中行模式识别的支持（SQL:2016 功能 R010 和 R020） ，我相信这将允许这样做。

与此同时，这应该做你需要的

WITH T AS
(
SELECT *, 
       LAG(Id) OVER (ORDER BY Id) AS PrevId, 
       LAG(value) OVER (ORDER BY Id) AS PrevValue,
       LEAD(Id) OVER (ORDER BY Id) AS NextId, 
       LEAD(value) OVER (ORDER BY Id) AS NextValue
FROM YourTable
)
SELECT PrevId, Id, NextId
FROM T
WHERE PrevValue = 50 AND Value =54 AND NextValue = 50

Answer 2

如果您想要更灵活的方法，可以使用cross apply ：

select t2.*
from t cross apply
     (select string_agg(id, ',') within group (order by date) as ids,
             string_agg(value, ',') within group (order by date) as vals
      from (select top (3) t2.*
            from t t2
            where t2.date >= t.date
            order by t2.date
           ) t2
     ) t2
where vals = '50,54,50';

这是一个 db<>fiddle。

如果支持string_agg()作为 window function，您可以使用：

select t.*
from (select t.*,
             string_agg(id, ',') within group (order by date) over (order by id rows between current row and 2 following) as ids,
             string_agg(value, ',') within group (order by date) over (order by id rows between current row and 2 following) as vals
      from t
     ) t
where vals = '50,54,50';

但很可惜，事实并非如此。

Answer 3

如果我的要求正确，您可以尝试在 LAG 和 LEAD 的帮助下开发的以下逻辑-

在这里演示

WITH CTE
AS
(
    SELECT Id,Date,
    LAG(value,2) OVER(ORDER BY id) lag_2,
    LAG(value,1) OVER(ORDER BY id) lag_1,
    Value c_val,
    LEAD(value,1) OVER(ORDER BY id) lead_1,
    LEAD(value,2) OVER(ORDER BY id) lead_2
    FROM your_table
)

SELECT Id,Date,
CASE 
    WHEN (lag_2 = 50 AND lag_1 = 54 AND c_val = 50) OR
         (lag_1 = 50 AND c_val = 54 AND lead_1 = 50) OR
         (c_val = 50 AND lead_1 = 54 AND lead_2 = 50)
         THEN (
             CASE 
                 WHEN lead_1 = 54 THEN 02
                 WHEN c_val = 54 THEN 03
                 WHEN lag_1 = 54 THEN 04
             END
         )
    ELSE c_val
END
FROM CTE