如何减去SQL中的数值范围？

Question

如何在SQL中减去数值范围？

例如：

SELECT 01 AS 'BEGIN', 99 AS 'END'
EXCEPT
SELECT 01 AS 'BEGIN', 15 AS 'END'

预期结果：

16 AS 'BEGIN', 99 AS 'END'

更完整的例子：

COMPLETE
BEGIN ---- END
 01         99

EXTRACT
BEGIN ---- END
 15         30

RESULT
BEGIN ---- END
 01         14
 31         99 

可能吗？

Answer 1

试试这个：

;WITH Complete AS (
   SELECT 1 AS [BEGIN], 99 AS [END]
), Extract AS (
   SELECT 1 AS [BEGIN], 15 AS [END]
), FreeSpace AS (
   SELECT (SELECT [BEGIN] - 1 FROM Extract) AS [LEFT],
          (SELECT [END] + 1 FROM Extract) AS [RIGHT]
)
SELECT [BEGIN], [END]
FROM (
SELECT [BEGIN], (SELECT [LEFT] FROM FreeSpace) AS [END]
FROM Complete

UNION ALL 

SELECT (SELECT [RIGHT] FROM FreeSpace) AS [BEGIN], [END]
FROM Complete ) AS t
WHERE [END] >= [BEGIN]

Demo here

CTE描述：

• Complete是我们希望减去另一个间隔
的间隔
• Extract是从Complete
中提取的时间间隔
• FreeSpace包含Extract
左侧和右侧的＆＃39;免费＆＃39; 边界

示例：

Extract:            15----------30
                  14              31  
FreeSpace: <------|               |------------->

使用14中的值31和FreeSpace构建Extract左侧和右侧的两个可能的非重叠区间。

谓词：

WHERE [END] >= [BEGIN]

最后检查这两个区间是否真的存在。