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9.2

Syntax to get most recent data for each entity in a table

Asked by TruthHunter in Databases Miscellaneous, Data Mining, MySQL Server

Tags: SQL, All, NA

Hi,

I'm hoping this is a real easy way for someone to pick up 500 points.  :^)

The question at http://www.experts-exchange.com/Database/Miscellaneous/Q_22617791.html is almost what I'm looking for, but not quite.

I have a table with the following columns:

column A identifies the entity generating the data
column B contains the data
column C is the timestamp of when the data was generated

The entities in column A can be duplicates; i.e., an entity generates data and inserts a row into the table whenever it performs its test.

What I'm looking for is a single query to return the most recent data for each entity in the table.  In other words, if the table contains:

A            B           C
Entity1    Data1   2008-09-17 11:34:35
Entity2    Data2   2008-09-17 11:36:28
Entity3    Data3   2008-09-17 11:39:54
Entity2    Data4   2008-09-17 11:45:10
Entity1    Data5   2008-09-17 11:50:07

How can I set up a query such that it would return just:

A            B           C
Entity1    Data5   2008-09-17 11:50:07
Entity2    Data4   2008-09-17 11:45:10
Entity3    Data3   2008-09-17 11:39:54

Actually, I don't really even need column C in the SELECT statement - I just need it to determine the most recent record for each entity.  Also, there may be another column in addition to column A that I might want to retrieve to further identify the entity, but it is just as unique as column A (e.g., column A is an entity ID, the other is an entity description).

Max points because it's urgent - and hopefully simple!  Thanks again.
[+][-]09/17/08 10:20 AM, ID: 22501218Accepted Solution

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Zones: Databases Miscellaneous, Data Mining, MySQL Server
Tags: SQL, All, NA
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Solution Provided By: matthewspatrick
Participating Experts: 2
Solution Grade: A
 
[+][-]09/17/08 10:22 AM, ID: 22501230Expert Comment

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[+][-]09/17/08 10:52 AM, ID: 22501594Author Comment

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[+][-]09/17/08 11:19 AM, ID: 22501924Author Comment

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