Home/ Questions/Q 320113
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-12T08:43:25+00:00

We use a monitoring solution (zabbix). It stores trends data (MySQL 5.X) using a

  • 0

We use a monitoring solution (zabbix). It stores trends data (MySQL 5.X) using a table called trends_uint with the following structure (simplified):

itemid    clock        value_avg
1         1238774400   100
1         1250773900   70
1         1250773200   50

The clock field stores datetime values using Unix time.

I’m trying to extract a report to see the consumption of a monitored item. I thought doing this by selecting the oldest record and the newest record. I achieved it doing the following:

SELECT
(SELECT t.clock FROM trends_uint t WHERE t.itemid = 1 AND t.clock IN (SELECT MIN(t.clock) FROM trends_uint t WHERE t.itemid = 1)) AS minClock,
(SELECT t.value_avg FROM trends_uint t WHERE t.itemid = 1 AND t.clock IN (SELECT MIN(t.clock) FROM trends_uint t WHERE t.itemid = 1)) AS minValueAvg,
(SELECT t.clock FROM trends_uint t WHERE t.itemid = 1 AND t.clock IN (SELECT MAX(t.clock) FROM trends_uint t WHERE t.itemid = 1)) AS maxClock,
(SELECT t.value_avg FROM trends_uint t WHERE t.itemid = 1 AND t.clock IN (SELECT MAX(t.clock) FROM trends_uint t WHERE t.itemid = 1)) AS maxValueAvg,
(SELECT maxClock - minClock) AS timeGap,
(SELECT minValueAvg - maxValueAvg) AS valueGap,
(SELECT timeGap/86400) AS daysGap,
(SELECT valueGap/daysGap/1024/1024) AS consumeMB

My problem is that I have lot’s servers from which I want to calculate the consumption. I don’t want to change the query for which one (changing the itemid).

The system has another table (items) from which I could extract the items that I need to put into the report. Something like SELECT itemid FROM items WHERE ...

So this is my question: instead of using a hardcoded itemid, is it possible to make it “dynamic”, for instance using the returned codes from another query (ex.: SELECT ... FROM ... WHERE itemid IN (SELECT itemid FROM items WHERE ...)?

TIA,

Bob

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    It looks like what you want is to use either your programming language’s or MySQL user-defined variables to store the ID you selected once and reuse it.

    I’m assuming you’re using some sort of a language, say PHP, to wrap around these calls.

    You can then:

    • do a SELECT on the itemid, save it as $itemid, and then pass in to your SELECT or

    • use MySQL user-defined variables and save the itemid, with something like

      SET @itemid=SELECT itemid FROM trends_uint WHERE ….

      SELECT …. WHERE t.itemid = @itemid ….

    • 0