Home/ Questions/Q 8324609
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-06-09T00:08:12+00:00

Preferably without downloading the entire database and scanning each item, is there a MySQL

  • 0

Preferably without downloading the entire database and scanning each item, is there a MySQL query that could access this table:

__________________________________
|   ColID   |      Timestamp      |
|___________|_____________________|
|_____2_____|_2012-08-01_12:00:00_|
|_____1_____|_2012-08-01_12:01:00_|
|_____3_____|_2012-08-01_12:02:00_|
|_____3_____|_2012-08-01_12:03:00_|
|_____2_____|_2012-08-01_12:04:00_|
|_____3_____|_2012-08-01_12:05:00_|

And return only these rows:

__________________________________
|   ColID   |      Timestamp      |
|___________|_____________________|
|_____1_____|_2012-08-01_12:01:00_|
|_____2_____|_2012-08-01_12:04:00_|
|_____3_____|_2012-08-01_12:05:00_|

So as to extract only one of each ColID with the highest Timestamp

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    Use GROUP BY with MAX:

    SELECT   ColID, MAX(Timestamp) AS Timestamp
FROM     tbl
GROUP BY ColID

    Also, just a tip you may want to keep in mind for the future: if you wanted to also select other columns that might be in the same table for each maximum ColID, you cannot select it directly in the above query due to the nature of GROUP BY. You will need to wrap the query in a joined subselect joining on both the id and date columns:

    SELECT b.*
FROM   tbl a
JOIN   (
       SELECT   ColID, MAX(Timestamp) AS max_timestamp
       FROM     tbl
       GROUP BY ColID
       ) b ON a.ColID = b.ColID AND a.max_timestamp = b.Timestamp
    • 0