如何查找两个可变日期之间的重复项

Question

我有以下 table:

id | whenCreated    | callingNumber |
---|--------------------------------|
1  | 1-1-2016 9:00  | 0612345678    |
2  | 1-1-2016 9:10  | 0623456789    |
3  | 1-1-2016 9:55  | 0612345678    |
4  | 1-1-2016 10:15 | 0623456789    |
5  | 1-1-2016 11:00 | 0623456789    |
etc.

Datatypes:
id = int (AI)
whenCreated = datetime
callingNumber = varchar

我想分析有多少人在上次通话后的一段时间内（例如，假设 1 小时）回电。为此，我想找出前一段时间有人打过电话的次数。在这个例子中，结果应该是这样的：

id | whenCreated    | callingNumber | prevCalls |
---|--------------------------------|-----------|
1  | 1-1-2016 9:00  | 0612345678    | 0         | < 0, because no previous calls
2  | 1-1-2016 9:10  | 0623456789    | 0         | < 0, because no previous calls
3  | 1-1-2016 9:55  | 0612345678    | 1         | < 1, because one call from this number in the last hour
4  | 1-1-2016 10:15 | 0623456789    | 0         | < 0, there was one earlier call from this number, but it was more than an hour ago
5  | 1-1-2016 11:00 | 0623456789    | 1         | < 1, because one call from this number in the last hour
etc.

有什么方法可以用 MySQL 中的一个查询来做到这一点？还是我必须运行为此编写脚本？（我知道如何单独为每一行执行此操作，但我似乎无法通过一个查询找到一种方法）。

Answer 1

您可以使用相关子查询来完成：

SELECT id, whenCreated, callingNumber,
       (SELECT COUNT(*)
        FROM mytable AS t2
        WHERE t2.callingNumber = t1.callingNumber AND
              t2.id < t1.id AND 
              TIMESTAMPDIFF(MINUTE, t2.whenCreated, t1.whenCreated) < 60)
FROM mytable AS t1

查询使用 TIMESTAMPDIFF 计算两个 whenCreated 值之间的分钟差。

Demo here

如何查找两个可变日期之间的重复项

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