检查范围是否重叠

Question

我有一个 table 这样的：

Id  min_val  max_val
1   5        7
2   8        12
3   4        6

如果 min_val 和 max_val 与任何其他 ID 重叠，我想得到 True/False。所以，结果如下：

Id result
1  True  
2  False 
3  True

谢谢。

Answer 1

一种方法使用 exists:

select t.*,
       (exists (select 1
                from t t2
                where t2.id <> t.id and
                      t2.max_val > t.min_val and
                      t2.min_val < t.max_val
               )
       ) as result;
from t;

另一种方法使用 window 函数。如果月经可以同时开始就有点棘手了，但是思路是：

select t.*,
       (max(max_val) over (order by min_val range between unbounded preceding and 1 preceding) > min_val) or
        min(min_val) over (order by max_val desc range between unbounded preceding and current row)
       ) as result
from t;

Answer 2

这可能有点矫枉过正，但您可以使用 JOIN，如下所示，不仅可以了解是否存在重叠，还可以了解重叠的内容：

SELECT t.id, tOther.id As overlappingId
FROM t
LEFT JOIN t AS tOther 
   ON t.id <> tOther.id            -- Not the same record
   AND t.min_val < tOther.max_val  -- Starts before "other" ends
   AND t.max_val > tOther.min_val  -- Ends after "other" starts
;

如果每个 t 只需要一个结果行，可以使用聚合调整查询。

SELECT t.id
    , COUNT(tOther.id) AS overlappingCount      -- Count ignores null values
    , GROUP_CONCAT(tOther.id) AS overlappingIDs -- Will be null if no overlaps
FROM t
LEFT JOIN t AS tOther 
   ON t.id <> tOther.id            -- Not the same record
   AND t.min_val < tOther.max_val  -- Starts before "other" ends
   AND t.max_val > tOther.min_val  -- Ends after "other" starts
GROUP BY t.id
;

如果您将共享边界算作重叠，只需将 > 和 < 分别更改为 >= 和 <=。

Answer 3

SELECT t2.id, 

CASE WHEN t2.id IN
(SELECT DISTINCT t.id
FROM tab1 as t
LEFT JOIN tab1 AS t1
WHERE t.id <> t1.id AND (t.min_val < t1.max_val AND t.max_val > t.min_val)) 
THEN "True" ELSE "False" END AS Results

FROM tab1 as t2

这对我有用。感谢@Uueerdo 和@Gordon Linoff

检查范围是否重叠

Check if ranges are overlapping

mysql

sql

sqlite

gaps-and-islands