MySQL GROUP BY DateTime +/- 3 seconds

by

I’m using Tom H.’s excellent idea but doing it a little differently here:

Instead of finding all the rows that are the beginnings of chains, we can find all times that are the beginnings of chains, then go back and ifnd the rows that match the times.

Query #1 here should tell you which times are the beginnings of chains by finding which times do not have any times below them but within 3 seconds:

SELECT DISTINCT Timestamp
FROM Table a
LEFT JOIN Table b
ON (b.Timestamp >= a.TimeStamp - INTERVAL 3 SECONDS
    AND b.Timestamp < a.Timestamp)
WHERE b.Timestamp IS NULL

And then for each row, we can find the largest chain-starting timestamp that is less than our timestamp with Query #2:

SELECT Table.id, MAX(StartOfChains.TimeStamp) AS ChainStartTime
FROM Table
JOIN ([query #1]) StartofChains
ON Table.Timestamp >= StartOfChains.TimeStamp
GROUP BY Table.id

Once we have that, we can GROUP BY it as you wanted.

SELECT COUNT(*) --or whatever
FROM Table
JOIN ([query #2]) GroupingQuery
ON Table.id = GroupingQuery.id
GROUP BY GroupingQuery.ChainStartTime

I’m not entirely sure this is distinct enough from Tom H’s answer to be posted separately, but it sounded like you were having trouble with implementation, and I was thinking about it, so I thought I’d post again. Good luck!

More Related Contents:

  1. Using LIMIT within GROUP BY to get N results per group?
  2. Error related to only_full_group_by when executing a query in MySql
  3. MySQL Query GROUP BY day / month / year
  4. Group by clause in mySQL and postgreSQL, why the error in postgreSQL?
  5. Strange duplicate behavior from GROUP_CONCAT of two LEFT JOINs of GROUP_BYs
  6. Grouping into interval of 5 minutes within a time range
  7. Retrieving the last record in each group – MySQL
  8. What’s faster, SELECT DISTINCT or GROUP BY in MySQL?
  9. Mysql query to dynamically convert rows to columns
  10. MySQL “Group By” and “Order By”
  11. SELECT / GROUP BY – segments of time (10 seconds, 30 seconds, etc)
  12. Group mysql query by 15 min intervals
  13. In SQL, how to select the top 2 rows for each group
  14. SQL Query to get column values that correspond with MAX value of another column?
  15. MySQL Group By and Sum total value of other column
  16. Is it possible to GROUP BY multiple columns using MySQL?
  17. Using Count to find the number of occurrences
  18. What does SQL clause “GROUP BY 1” mean?
  19. Using ORDER BY and GROUP BY together
  20. MySQL: How do I join same table multiple times?
  21. GROUP BY – do not group NULL
  22. MySQL Group By Hours
  23. mysql count group by having
  24. SQL query with avg and group by
  25. MYSQL OR vs IN performance
  26. How to find gaps in sequential numbering in mysql?
  27. MySql export schema without data
  28. limiting the rows to where the sum a column equals a certain value in MySQL
  29. How to select column names dynamically in mySQL
  30. How to select data where a field has a min value in MySQL?

Leave a Comment