This optional parameter defines an SQL query which will be
used to determine the total of octets 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 of
the start time of the query. It is expected to return a single field
containing the total octets.
It is used to get a count for the
following check items:
- Max-Hourly-Octets
- Max-Daily-Octets
- Max-Monthly-Octets