MySQL数据库如何判断时间段是否重合的两种方法
两种写法。如图，4种重合情况和2种不重合情况。
第一种写法：
— 时间段 a,b
SELECT * FROM table WHERE
(start_time >= a and end_time <= b) — 被包含了
or (end_time >= a and end_time <=b)
or (start_time >= a and start_time <=b)
or (start_time <= a and end_time >=b)
SELECT * FROM table WHERE
(start_time >= a and end_time <= b) — 被包含了
or (end_time >= a and end_time <=b)
or (start_time >= a and start_time <=b)
or (start_time <= a and end_time >=b)
解析：where后的4个条件分别代表了图中4种重合的情况。
但是第一种情况被2和3包含了，所以简化一下写法：
SELECT * FROM table WHERE
(end_time >= a and end_time <=b)
or (start_time >= a and start_time <=b)
or (start_time <= a and end_time >=b);
(end_time >= a and end_time <=b)
or (start_time >= a and start_time <=b)
or (start_time <= a and end_time >=b);
第二种写法：
SELECT * FROM table WHERE not (start_time > b or end_time < a);
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