我的数据库中有这样的事件数据：
time | obj | type
-------------------
0012 23 start
0014 24 start
0023 25 start
0034 23 end
0056 26 start
0058 23 start (reusing obj 23)
0060 25 end
0100 24 end
0101 23 end
0107 26 end
...
我想通过开始事件时间对其进行排序，然后是同一对象的结束事件：
time | obj | type
-------------------
0012 23 start
0034 23 end
0014 24 start
0100 24 end
0023 25 start
0060 25 end
0056 26 start
0107 26 end
0058 23 start
0101 23 end
...
到目前为止，我没有想出一个SQL查询来输出这样的数据。当然，我可以查询所有启动事件，然后在每行查询来自我的C API的相应结束事件后，但我有多个10.000结束事件，这看起来效率很低。
编辑：对不起，我忘了提到obj号码可以重复使用（并且有一个唯一的id行）当我第一次问这个问题时，我现在更新了样本。
有什么想法吗？
答案 0 :(得分：1)
如果结束时间总是在开始时间之后，这应该有效
select time,obj,type
from t order by obj,time;
但你也可以在排序
中使用一个案例陈述select time,obj,type
from t
order by obj,
case when type = 'start' then 1
else 2
end;
如果obj被重用，那么棘手的一点是在开始命令之前将开始类型的id分配给结束类型
select t1.time,t1.obj,t1.type, t1.id,
case when t2.id is null then t1.id
else t2.id
end as startid
from t t1
left join t t2 on t2.obj = t1.obj and t2.id = (select max(t.id) from t where t.obj = t1.obj and t.id < t1.id and t1.type = 'end')
order by startid,id
+------+------+-------+----+---------+
| time | obj | type | id | startid |
+------+------+-------+----+---------+
| 12 | 23 | start | 1 | 1 |
| 34 | 23 | end | 4 | 1 |
| 14 | 24 | start | 2 | 2 |
| 100 | 24 | end | 8 | 2 |
| 23 | 25 | start | 3 | 3 |
| 60 | 25 | end | 7 | 3 |
| 56 | 26 | start | 5 | 5 |
| 107 | 26 | end | 12 | 5 |
| 58 | 23 | start | 6 | 6 |
| 101 | 23 | end | 9 | 6 |
| 102 | 23 | start | 10 | 10 |
| 103 | 23 | end | 11 | 10 |
+------+------+-------+----+---------+
12 rows in set (0.00 sec)
答案 1 :(得分：1)
您可以简单地依赖事件类型的顺序。因为e在s之前，然后排序desc。
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