[英]Search sequence pattern in SQL Server
我有這樣的記錄,我想在 SQL 服務器中按模式和序列(如(50,54,50))在值字段中搜索它應該返回 02,03,04 任何人都知道這樣做。
======================================
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
======================================
用戶語音站點上有一個請求添加對 T-SQL 中行模式識別的支持(SQL:2016 功能 R010 和 R020) ,我相信這將允許這樣做。
與此同時,這應該做你需要的
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
如果您想要更靈活的方法,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';
這是一個 db<>fiddle。
如果支持string_agg()
作為 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,事實並非如此。
如果我的要求正確,您可以嘗試在 LAG 和 LEAD 的幫助下開發的以下邏輯-
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
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