- What Grafana version and what operating system are you using?
- What are you trying to achieve?
Use Expression math along with a query that uses $variable.
- How are you trying to achieve it?
I created query “A” and query “B”, which use data from mysql. The sql queries use $variable.
SELECT UNIX_TIMESTAMP(cast(mplayers.registration as date)) as time_sec, count(*) as value, 'регистраций_новых_людей' FROM players as mplayers WHERE mplayers.registration BETWEEN cast($__timeFrom() as date) + interval 1 day AND cast($__timeTo() as date) + interval 1 day $filter GROUP BY time_sec ORDER BY time_sec ASC
SELECT UNIX_TIMESTAMP(cast(mplayers.registration as date)) as time_sec, sum((`mplayers`.`last_online` > (`mplayers`.`registration` + interval 1 day))) as value, 'зашел_через_24_часа_и_более' FROM players as mplayers WHERE mplayers.registration BETWEEN cast($__timeFrom() as date) + interval 1 day AND cast($__timeTo() as date) + interval 1 day $filter GROUP BY time_sec ORDER BY time_sec ASC
These sql queries use the grafana-variable $filter.
This variable is equal to the value “and multi = 0”.
Both queries work.
I also created an expression math “C” which equals “$A + $B”.
- What happened?
Graph “C” is not displayed, and graphs “A” and “B” disappear.
- What did you expect to happen?
I was expecting to see a C and A and B chart.
- Can you copy/paste the configuration(s) that you are having problems with?
- Did you receive any errors in the Grafana UI or in related logs? If so, please tell us exactly what they were.
In grafana 7.5.11 there are no errors in the GUI or in /var/log/grafana
But I tested grafana 8.2.5 and this problem is present there too. So, on version 8.2.5 in /var/log/grafana the error is displayed:
t=2021-11-21T03:50:50+0300 lvl=eror msg="expression request error" logger=context userId=1 orgId=1 uname=secret error="failed to execute query E: db query error: Error 1064: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '$filter\r\nGROUP BY time_sec\r\nORDER BY time_sec ASC' at line 6" remote_addr=secret t=2021-11-21T03:50:50+0300 lvl=eror msg="Request Completed" logger=context userId=1 orgId=1 uname=secret method=POST path=/api/ds/query status=500 remote_addr=secret time_ms=2 size=38 referer="http://secret:3000/d/ehJD-HZZk/registratsii?editPanel=25&orgId=1"
- Did you follow any online instructions? If so, what is the URL?