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MySQL Union select statements

that1guy15 asked
Last Modified: 2012-05-09
Hey all,

First off I am not by any means a DBA or a database guy. I can stumble around in MySQL enough to get what i want and break stuff :)

I have a database that is used for system monitoring. Events are entered into one table (status) and then over time "aged out" and moved to a second table (history). I have a query that will return the total number of each event over a given time frame. I use this to basically get a top 10 errors report for a given time frame.

This works great when i run the query against one table or the other. My problem is when i use the UNION ALL statement and combine the two into a single query. the query runs fine and gives me the proper results for each table. But it does not merge the same events from each table. So the returned list has duplicate events, one from each table. I would like to get only a single event for both tables and its combined count.

Here is the query i am running and a sample of what it returns.

Thanks for your help!

SELECT COUNT(summary) AS total_count, summary FROM history 
 AND severity = 3 GROUP BY summary UNION ALL 
SELECT COUNT(summary) AS total_count, summary FROM status 
 AND severity = 3 GROUP BY summary ORDER by total_count DESC;

| total_count | summary                |
|          60 | TIMEOUT14              |
|          54 | TIMEOUT14              |
|          53 | COMMERROR              |
|          48 | COMMERROR              |
|          48 | DURATIONTIMEOUT        |

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