How to create a MySQL query for time based elements with a 'safe window'?

Posted by pj4533 on Stack Overflow See other posts from Stack Overflow or by pj4533
Published on 2010-06-15T13:39:02Z Indexed on 2010/06/15 13:52 UTC
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Filed under:

sql

|

mysql

|

ruby-on-rails

|

mysql-query

I am no SQL expert, far from it. I am writing a Rails application, and I am new at that as well. I come from a desktop programming background.

My application has a table of data, one of the columns is the time at which the data was logged. I want to create a query with a 'safe window' around EACH row. By that I mean, it returns the first row, then for X minutes (based on the timelogged column) it won't return any data, once X minutes is up, it will return the next row.

For example:

ID | TimeLogged
1  | 3/5/2010 12:01:01
2  | 3/5/2010 12:01:50
3  | 3/5/2010 12:02:03
4  | 3/5/2010 12:10:30
5  | 3/5/2010 01:30:03
6  | 3/5/2010 01:31:05

With a 'safe window' of 5 minutes I want to create a query to return:

1  | 3/5/2010 12:01:01
4  | 3/5/2010 12:10:30
5  | 3/5/2010 01:30:03

(It skipped the 12:01:50 and 12:02:03 items because they occurred within 5 minutes of the first item.)

Another example, with a 'safe window' of 15 minutes I want to return:

1  | 3/5/2010 12:01:01
5  | 3/5/2010 01:30:03

Perhaps I have to just return all data and parse it myself?

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