在单个表sql中选择时间冲突

Question

我希望在特定日期获得时间冲突

我的桌子

| starttime | endtime  | day  | subject |
------------------------------------------
| 09:00:00  | 11:00:00 |  M   |   math  |
 -----------------------------------------
| 09:00:00  | 11:00:00 |  M   | science |
 -----------------------------------------
| 06:00:00  | 09:00:00 |  M   | History |
 ----------------------------------------- 
| 06:00:00  | 09:00:00 |  T   |   P.E.  |
 -----------------------------------------
| 10:00:00  | 12:00:00 |  M   | English |
 -----------------------------------------    

我想要的输出

| starttime | endtime  | day  | subject |
------------------------------------------
| 09:00:00  | 11:00:00 |  M   |   math  |
 -----------------------------------------
| 09:00:00  | 11:00:00 |  M   | science |
 -----------------------------------------
| 10:00:00  | 12:00:00 |  M   | English |
 -----------------------------------------

Answer 1

对我来说唯一有意义的问题的唯一解释是，您希望识别时间范围与一个或多个其他时间范围重叠（“冲突”）的记录。如果是这样，我们可以在重叠条件下进行自连接，然后保留那些有重叠的范围。

SELECT DISTINCT
    t1.starttime,
    t1.endtime,
    t1.day,
    t1.subject
FROM yourTable t1
LEFT JOIN yourTable t2
    ON
        (t1.starttime > t2.starttime AND t1.starttime < t2.endtime AND t1.day = t2.day) OR
        (t1.endtime > t2.starttime   AND t1.endtime < t2.endtime AND t1.day = t2.day) OR
        (t1.starttime = t2.starttime AND t1.endtime = t2.endtime AND t1.day = t2.day AND
         t1.subject <> t2.subject)
WHERE
    t2.starttime IS NOT NULL;

<强>输出：

    starttime   endtime day subject
1   07:00:00    10:00:00    T   History
2   07:00:00    10:00:00    T   P.E.

在这里演示：

Rextester