This optional parameter defines an SQL query which will be
used to determine the total of session times from a certain time until now
for a given user. Special characters are supported. %0 is replaced by the
user name being checked. %1 is replaced by the Unix epoch time in seconds
in the start time of the query. It is expected to return a single field
containing the total session time in seconds.
It is used to get a
count for the following check items:
- Max-Hourly-Session
- Max-Daily-Session
- Max-Monthly-Session