[SQL]連續範圍排除另一個範圍問題

sql islands and gaps problem. sql-server

石頭 2019-03-28 23:09:03 ‧ 3935 瀏覽

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在 S.O上有一個SQL問題Splits records based on range

在大家分享我的解法

有兩張表

Item Table

| Id | ItemId | FROM |  To |
|----|--------|------|-----|
|  1 |      1 |    1 | 100 |
|  2 |      1 |  101 | 500 |
|  3 |      1 |  600 | 700 |

ItemRange Table

| Id | ItemId | FROM | To |
|----|--------|------|----|
|  1 |      1 |   50 | 60 |
|  2 |      1 |   70 | 80 |

期望輸出

| ItemId | FROM |  TO |
|--------|------|-----|
|      1 |    1 |  49 |
|      1 |   61 |  69 |
|      1 |   81 | 500 |
|      1 |  600 | 700 |

SQLfiddle

問題描述：

提問者想要產生一個結果集，關於Item表依照 ItemId 創立 [FROM] 到 [TO] 的值，但要排除在
ItemRange表連續範圍內的值。

例如：
Item表有一列 1 ~ 100

| ItemId | FROM  |  To |
| 1      |    1  | 100 |

但由於ItemRange表有兩列 50 ~ 60和70 ~ 80

| ItemId | FROM  |  To |
| 1      |   50  | 60  |
| 1      |   70  | 80  |

所以這部份期望輸出，Item表要排除ItemRange表連續範圍數字

如下

| ItemId | FROM |  TO |
|--------|------|-----|
|      1 |    1 |  49 |
|      1 |   61 |  69 |
|      1 |   81 | xxx |

我看到連續範圍，就會聯想這個是一個(Islands and gaps problem)

我的想法是要先兩個full連續範圍資料表，我先使用CTE遞迴來實作

Item
ItemRange

之後再使用 except 對於 Item 排除 ItemRange 要排除的數字範圍

;WITH CTE AS (
  SELECT ItemId,[FROM],[TO]
  FROM Item
  UNION ALL
  SELECT ItemId,[FROM]+ 1,[TO]
  FROM CTE
  WHERE [FROM]+ 1 <= [TO]
), CTE2 AS(
  SELECT ItemId,[FROM],[TO]
  FROM ItemRange
  UNION ALL
  SELECT  ItemId,[FROM]+ 1,[TO]
  FROM CTE2
  WHERE [FROM]+ 1 <= [TO]
),CTE3 AS(
  SELECT ItemId,[FROM]
  FROM CTE
  except
  SELECT ItemId,[FROM]
  FROM CTE2
)

最後就是重頭戲，使用ROW_NUMBER + Window Function 做出標示連續範圍的群組

SELECT ItemId,
       MIN([FROM]) 'FROM',
       MAX([FROM]) 'TO'
FROM (
  SELECT ItemId,[FROM],[FROM] - ROW_NUMBER() OVER(ORDER BY [FROM]) grp
  FROM CTE3
) t1
GROUP BY grp,ItemId
option (maxrecursion 0)

解答SQLfiddle

目前提問者還有一個問題是他的範圍太大，導致執行效能不是很好這個問題我目前還沒有特別的解法歡迎有想法的大大可以提供建議

P.S. 我覺得此問題很清楚，但我不知道為什麼會被投Close

直播研討會

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1 則留言

小碼農米爾

iT邦高手 1 級 ‧ 2019-04-05 04:57:27

這題好難，想試試看能不能不用迴圈寫出來。

作法分為兩階段:

先合併 Item 連續或重疊的區間

SELECT A.ItemId, A.[FROM],
	   CASE WHEN A.[TO] > B.[TO] THEN A.[TO] ELSE B.[TO] END AS [TO],
	   --重新編一個Id
	   A.Id+'-1' AS Id,
	   A.Id AS PId1,
	   CAST(B.Id AS NVARCHAR(MAX)) AS PId2
FROM CTE_MERGE AS A

找到可以合併的區間後，會加入一筆新的區間，並紀錄 PId1、PId2 代表被合併的兩個區間，之後 CLEAR CTE 中就可以利用 PId1、PId2 排除不要的資料。

將 ItemRange 從 Item 內排除

CROSS APPLY (VALUES(1),(2)) AS C(G)

這邊需要把區間拆開，一直想不到用什麼方法可以將一筆資料拆成兩筆，大部分時間是卡在這裡，最後發現可以用 CROSS APPLY + VALUES，在配合 CASE WHEN 就可以漂亮的把區間拆開。

CASE WHEN G=1 THEN A.[FROM] ELSE B.[TO]+1 END AS [FROM],
CASE WHEN G=1 THEN B.[FROM]-1 ELSE A.[TO] END AS [TO],

最後這邊是關鍵，本來我以為需要寫很多判斷，因為 Item、ItemRange 交集會產生很多種可能，但很神奇的是只用兩行就完成了，出乎意料。

情況如下:

第一種:

A:10-20   [   ]      
B:18-25      [   ]   

Range1: 10-17
Range2: 26-20

第二種:

A:10-20      [   ]      
B:05-12   [   ]   

Range1: 10-4
Range2: 13-20

第三種:

A:10-20   [   ]      
B:12-18    [ ]   

Range1: 10-11
Range2: 19-20

第四種:

A:10-20    [ ]      
B:05-25   [   ]   

Range1: 10-04
Range2: 16-20

第五種:

A:10-20   [   ]      
B:10-20   [   ]   

Range1: 10-09
Range2: 21-20

最後只要把負區間去掉，就是期望的結果。

結果

 ItemId	 FROM	 TO
--------|-----|-------
   1      1	     49
   1      61	 69
   1      81	 500
   1      600	 700

總共用了四個 CTE 完成:

DECLARE @Item TABLE
(
	[Id] INT,
	[ItemId] INT, 
	[FROM] INT,
	[TO] INT
)

DECLARE @ItemRange TABLE
(
	[Id] INT,
	[ItemId] INT, 
	[FROM] INT,
	[TO] INT
)

INSERT INTO @Item VALUES
(1,1,1,100),
(2,1,101,500),
(3,1,600,700)

INSERT INTO @ItemRange VALUES
(1,1,50,60),
(2,1,70,80)

--合併Item重疊部分
--排除被完全包含的區間 A[ B[] ]
--並合併下面這種類型的區間
-- A[   ]
-- B    [   ]
;WITH CTE_MERGE AS
(
	SELECT A.ItemId, A.[FROM], A.[TO],
	       CAST(A.Id AS NVARCHAR(MAX)) AS Id,
	       CAST(NULL AS NVARCHAR(MAX)) AS PId1, 
		   CAST(NULL AS NVARCHAR(MAX)) AS PId2
	FROM @Item AS A
	LEFT JOIN @Item AS B
		ON B.ItemId=A.ItemId AND
		   --排除A被包在B的資料，這種資料會造成下方無窮迴圈
		   B.Id<>A.Id AND
		   B.[FROM] <= A.[FROM] AND B.[TO] >= A.[TO]
	WHERE B.Id IS NULL
	UNION ALL
	SELECT A.ItemId, A.[FROM],
		   CASE WHEN A.[TO] > B.[TO] THEN A.[TO] ELSE B.[TO] END AS [TO],
		   --重新編一個Id
		   A.Id+'-1' AS Id,
		   A.Id AS PId1,
		   CAST(B.Id AS NVARCHAR(MAX)) AS PId2
	FROM CTE_MERGE AS A
	CROSS APPLY (
		SELECT *
		FROM (
			SELECT *, ROW_NUMBER() OVER (ORDER BY B.Id) AS R FROM @Item AS B
			WHERE B.ItemId=A.ItemId AND
			      --找到可以合併的區間
			      CAST(B.Id AS NVARCHAR(MAX))<>A.Id AND
				  A.[TO]+1 >= B.[FROM] AND A.[TO]+1 <= B.[TO]
		) AS X
		WHERE X.R=1
	) AS B
)

--SELECT * FROM CTE_MERGE

--排除遞迴中殘留的部分
,CTE_MERGE_CLEAR AS 
(
	SELECT A.Id, A.ItemId, A.[FROM], A.[TO]
	FROM CTE_MERGE AS A
	LEFT JOIN CTE_MERGE AS B ON A.Id=B.PId1 OR A.Id=B.PId2
	--沒有父Id的資料才是最後結果
	WHERE B.Id IS NULL
)

--SELECT * FROM CTE_MERGE_CLEAR

--排除ItemRange部分
--判斷重疊有這五種可能
-- A [   ]  [ ]    [   ] [   ]   [   ]
-- B  [ ]  [   ] [   ]     [   ] [   ]
,CTE AS
(
	SELECT ItemId, [FROM], [TO], Id,
		   CAST(NULL AS NVARCHAR(MAX)) AS PId
	FROM CTE_MERGE_CLEAR
	UNION ALL
	SELECT *
	FROM (
		SELECT A.ItemId,
		       CASE WHEN G=1 THEN A.[FROM] ELSE B.[TO]+1 END AS [FROM],
		       CASE WHEN G=1 THEN B.[FROM]-1 ELSE A.[TO] END AS [TO],
			   --重新編一個Id
		       CASE WHEN G=1 THEN A.Id+'-1' ELSE A.Id+'-2' END AS Id,
			   A.Id AS PId
		FROM CTE AS A
		CROSS APPLY (
			SELECT *
			FROM (
				SELECT *, ROW_NUMBER() OVER (ORDER BY B.Id) AS R FROM @ItemRange AS B
				WHERE B.ItemId=A.ItemId AND
				      --找到Item和ItemRange重疊的部分
					  ((A.[FROM] >= B.[FROM] AND A.[FROM] <= B.[TO]) OR
					   (A.[TO] >= B.[FROM] AND A.[TO] <= B.[TO]) OR
					   (A.[FROM] <= B.[FROM] AND A.[TO] >= B.[TO]))
			) AS X
			--取一筆就好，一次迴圈拆一次區間就好
			WHERE X.R=1
		) AS B
		--將一筆資料拆成兩筆
		CROSS APPLY (VALUES(1),(2)) AS C(G)
	) AS X
	--負區間就不要了
	WHERE X.[TO]-X.[FROM] > 0
)

--SELECT * FROM CTE

--排除遞迴中殘留的部分
,CTE_CLEAR AS 
(
	SELECT A.ItemId, A.[FROM], A.[TO]
	FROM CTE AS A
	LEFT JOIN CTE AS B ON A.Id=B.PId
	--沒有父Id的資料才是最後結果
	WHERE B.Id IS NULL
)

SELECT * 
FROM CTE_CLEAR
ORDER BY ItemId, [FROM]

SQL

CTE 效能不是很好，用 TEMP TABLE 優化:

DECLARE @Item TABLE
(
	[Id] INT,
	[ItemId] INT, 
	[FROM] INT,
	[TO] INT
)

DECLARE @ItemRange TABLE
(
	[Id] INT,
	[ItemId] INT, 
	[FROM] INT,
	[TO] INT
)

INSERT INTO @Item VALUES
(1,1,1,100),
(2,1,101,500),
(3,1,600,700)

INSERT INTO @ItemRange VALUES
(1,1,50,60),
(2,1,70,80)

--暫存表優化CTE
DECLARE @TEMP_MERGE TABLE
(
	ItemId INT, 
	[FROM] INT,
	[TO] INT,
	Id NVARCHAR(MAX),
	PId1 NVARCHAR(MAX),
	PId2 NVARCHAR(MAX)
)
DECLARE @TEMP_MERGE_CLEAR TABLE
(
	Id NVARCHAR(MAX),
	ItemId INT, 
	[FROM] INT,
	[TO] INT
)
DECLARE @TEMP TABLE
(
	ItemId INT, 
	[FROM] INT,
	[TO] INT,
	Id NVARCHAR(MAX),
	PId NVARCHAR(MAX)
)

--合併Item重疊部分
;WITH CTE_MERGE AS
(
	SELECT A.ItemId, A.[FROM], A.[TO],
	       CAST(A.Id AS NVARCHAR(MAX)) AS Id,
	       CAST(NULL AS NVARCHAR(MAX)) AS PId1, 
		   CAST(NULL AS NVARCHAR(MAX)) AS PId2
	FROM @Item AS A
	LEFT JOIN @Item AS B
		ON B.ItemId=A.ItemId AND
		   B.Id<>A.Id AND
		   B.[FROM] <= A.[FROM] AND B.[TO] >= A.[TO]
	WHERE B.Id IS NULL
	UNION ALL
	SELECT A.ItemId, A.[FROM],
		   CASE WHEN A.[TO] > B.[TO] THEN A.[TO] ELSE B.[TO] END AS [TO],
		   A.Id+'-1' AS Id, 
		   A.Id AS PId1,
		   CAST(B.Id AS NVARCHAR(MAX)) AS PId2
	FROM CTE_MERGE AS A
	CROSS APPLY (
		SELECT *
		FROM (
			SELECT *, ROW_NUMBER() OVER (ORDER BY B.Id) AS R FROM @Item AS B
			WHERE B.ItemId=A.ItemId AND
			      CAST(B.Id AS NVARCHAR(MAX))<>A.Id AND
				  A.[TO]+1 >= B.[FROM] AND A.[TO]+1 <= B.[TO]
		) AS X
		WHERE X.R=1
	) AS B
)

INSERT INTO @TEMP_MERGE 
SELECT * FROM CTE_MERGE

--SELECT * FROM @TEMP_MERGE

--排除遞迴中殘留的部分
;WITH CTE_MERGE_CLEAR AS 
(
	SELECT A.Id, A.ItemId, A.[FROM], A.[TO]
	FROM @TEMP_MERGE AS A
	LEFT JOIN @TEMP_MERGE AS B ON A.Id=B.PId1 OR A.Id=B.PId2
	WHERE B.Id IS NULL
)

INSERT INTO @TEMP_MERGE_CLEAR 
SELECT * FROM CTE_MERGE_CLEAR

--SELECT * FROM @TEMP_MERGE_CLEAR

--排除ItemRange部分
;WITH CTE AS
(
	SELECT ItemId, [FROM], [TO], Id,
		   CAST(NULL AS NVARCHAR(MAX)) AS PId
	FROM @TEMP_MERGE_CLEAR
	UNION ALL
	SELECT *
	FROM (
		SELECT A.ItemId,
		       CASE WHEN G=1 THEN A.[FROM] ELSE B.[TO]+1 END AS [FROM],
		       CASE WHEN G=1 THEN B.[FROM]-1 ELSE A.[TO] END AS [TO],
		       CASE WHEN G=1 THEN A.Id+'-1' ELSE A.Id+'-2' END AS Id,
			   A.Id AS PId
		FROM CTE AS A
		CROSS APPLY (
			SELECT *
			FROM (
				SELECT *, ROW_NUMBER() OVER (ORDER BY B.Id) AS R FROM @ItemRange AS B
				WHERE B.ItemId=A.ItemId AND
					  ((A.[FROM] >= B.[FROM] AND A.[FROM] <= B.[TO]) OR
					   (A.[TO] >= B.[FROM] AND A.[TO] <= B.[TO]) OR
					   (A.[FROM] <= B.[FROM] AND A.[TO] >= B.[TO]))
			) AS X
			WHERE X.R=1
		) AS B
		CROSS APPLY (VALUES(1),(2)) AS C(G)
	) AS X
	WHERE X.[TO]-X.[FROM] > 0
)

INSERT INTO @TEMP
SELECT * FROM CTE

--SELECT * FROM @TEMP

--排除遞迴中殘留的部分
;WITH CTE_CLEAR AS 
(
	SELECT A.ItemId, A.[FROM], A.[TO]
	FROM @TEMP AS A
	LEFT JOIN @TEMP AS B ON A.Id=B.PId
	WHERE B.Id IS NULL
)

SELECT * 
FROM CTE_CLEAR
ORDER BY ItemId, [FROM]

SQL