sql中查找模式並計算有多少次出現

Question

數據給

22 
22 
22 
22 
22 
36 
54 
40 
22 
22 
22 
22 
36 
22 
22 
54 
22 
22 

這是在表中的列。使用SQL查詢，我們需要找出圖案如 22 36 54 40是第一圖案然後22圖36是第二和22 54是第三圖案。

Answer 1

您應該使用LEAD來獲取下一行的值，看看它是否是22，並使用它來擺脫列中所有額外的22。東西這種效果：

declare @t table (id int identity(1,1) not null, n int) 
insert into @t 
select 22 union all 
select 22 union all 
select 22 union all 
select 22 union all 
select 22 union all 
select 36 union all 
select 54 union all 
select 40 union all 
select 22 union all 
select 22 union all 
select 22 union all 
select 22 union all 
select 36 union all 
select 22 union all 
select 22 union all 
select 54 union all 
select 22 union all 
select 22 

select id,n from (select id,n ,lead(n) over (order by id) 
as lead_val from @t) t where n<>22 or lead_val<>22 

此輸出：

5 22 
6 36 
7 54 
8 40 
12 22 
13 36 
15 22 
16 54 

Answer 2

的PostgreSQL

假設：

• 有確定所述元素的順序的列
• 種所有模式與22

---

select  array_to_string(array_agg(val order by i),',') as pattern 
      ,min (i)          as from_i 
      ,max (i)          as to_i 
      ,count(*)          as pattern_length   

from  (select i,val 
        ,count(case when val = 22 then 1 end) over 
        (
         order by i 
         rows unbounded preceding 
        ) as pattern_id 

      from mytable 
      ) t 

group by pattern_id 

having  count(*)>1 
; 

---

+-------------+--------+------+----------------+ 
| pattern | from_i | to_i | pattern_length | 
+-------------+--------+------+----------------+ 
| 22,36,54,40 |  5 | 8 |    4 | 
| 22,36  |  12 | 13 |    2 | 
| 22,54  |  15 | 16 |    2 | 
+-------------+--------+------+----------------+