Chart Data Query Language

The Data Query Language is a simple language to query summarized (hourly, daily...) meteorological data from stations. The structure of a query is:

$fieldA[, ...] [from $table] $interval_expr [compare $time_expr]

You can also group by date and aggregate fields

$agg_fn($fieldA)[, ...] [from $table] $interval_expr group by $group_interval [compare $cmp_interval]

Notes

If not specified, the table defaults to 'current'
'current' table accepts 'current fields', all the other tables accept 'summarized fields'

Current fields

Current fields contain raw data of the stations (less than 1 minute aggregates), and are only used with the current table

Field	Description	Type
`rate.max.dt`	Maximum rain rate (Date)	datetime
`wc.min.dt`	Minimum windchill (Date)	datetime
`hi.max.dt`	Maximum Heat Index (Date)	datetime
`rate.max`	Maximum rain rate	double
`gust.dt`	Maximum wind gust (Date)	datetime
`wc.min`	Minimum windchill	double
`hi.max`	Maximum Heat Index	double
`t.in`	Interior temperature	double
`h.in`	Interior humidity	double
`wind`	Wind speed	double
`gust`	Maximum wind gust	double
`rain`	Total rain	double
`rate`	Average rain rate	double
`dew`	Dew point	double
`wc`	Windchill	double
`hi`	Heat index	double
`t`	Temperature	double
`h`	Humidity	double
`b`	Barometer	double

Summarized fields

Summarized fields are directly related to data emitted by the station with a simple aggregation applied afterwards. The complete list of fields is:

Field	Description	Type
`t.in.max.dt`	Maximum interior temperature (Date)	datetime
`t.in.min.dt`	Minimum interior temperature (Date)	datetime
`h.in.max.dt`	Maximum interior humidity (Date)	datetime
`h.in.min.dt`	Minimum interior humidity (Date)	datetime
`rate.max.dt`	Maximum rain rate (Date)	datetime
`dew.max.dt`	Maximum dewpoint (Date)	datetime
`dew.min.dt`	Minimum dewpoint (Date)	datetime
`bar.max.dt`	Maximum barometer (Date)	datetime
`bar.min.dt`	Minimum barometer (Date)	datetime
`wc.min.dt`	Minimum windchill (Date)	datetime
`hi.max.dt`	Maximum heat index (Date)	datetime
`t.max.dt`	Maximum temperature (Date)	datetime
`t.min.dt`	Minimum temperature (Date)	datetime
`t.in.max`	Maximum interior temperature	double
`t.in.avg`	Average interior temperature	double
`t.in.min`	Minimum interior temperature	double
`h.max.dt`	Maximum humidity (Date)	datetime
`h.min.dt`	Minimum humidity (Date)	datetime
`h.in.max`	Maximum interior humidity	double
`h.in.avg`	Average interior humidity	double
`h.in.min`	Minimum interior humidity	double
`rate.max`	Maximum rain rate	double
`dew.max`	Maximum dewpoint	double
`dew.avg`	Average dewpoint	double
`dew.min`	Minimum dewpoint	double
`bar.max`	Maximum barometer	double
`bar.avg`	Average barometer	double
`bar.min`	Minimum barometer	double
`gust.dt`	Maximum wind gust (Date)	datetime
`t.ampl`	Temperature amplitude (T.max-T.min)	double
`wc.avg`	Average windchill	double
`wc.min`	Minimum windchill	double
`hi.max`	Maximum heat index	double
`hi.avg`	Average heat index	double
`t.max`	Maximum temperature	double
`t.avg`	Average temperature	double
`t.min`	Minimum temperature	double
`h.max`	Maximum humidity	double
`h.avg`	Average humidity	double
`h.min`	Minimum humidity	double
`wind`	Average wind speed	double
`gust`	Maximum wind gust	double
`rain`	Total rain	double
`rate`	Average rain rate	double

Tables

All the tables contain the same kind of information, but summarized into different date ranges:

Table
`current`
`hourly`
`daily`
`monthly`

Interval expression

An interval expression defines the range of time the data will be queried. There are several predefined intervals:

last $NUMBER hours
last $NUMBER days
last $NUMBER weeks
last $NUMBER months
last year
last $NUMBER years
last winter: last finished meteorological winter (3 months, from december to february)
$month: a full month using strings (january, february...) of the current year
$month $year: a full month using strings (january, february...) and full year (2024)

Grouping intervals

Data can be grouped by date, using the following values:

day
week
month

Aggregation functions

Once data has been grouped, fields should be aggregated used the following functions:

max
avg
min

Compare intervals

A chart can be duplicated and be compared with past dates. The valid intervals are:

$NUMBER years
$NUMBER weeks
$NUMBER hours
$NUMBER months
$NUMBER days