Max

aggregation-functions max(imum)

syntax

  • max(a)
  • max(a, relation)

definition

  • max(a) results in a parameter with the maximum of the non null values of attribute a.
  • max(a, relation) results in an attribute with the maximum of the non null values of attribute a, grouped by relation. The domain-unit of the resulting attribute is the values-unit of the relation.

description

The max function is not defined for boolean data-item, use the all function instead.

If there are no values to be aggregated for a group, the resulting value will be the minimum value for the value-type of attribute a (in the example: 0, the minimum value for the value type: uint32).

applies to

  • attribute a with Numeric, Point or string value type
  • relation with value type of the group CanBeDomainUnit

conditions

  1. The values unit of the resulting data item should match with regard to value type and metric with the values unit of attribute a.
  2. The domain of argument a and relation must match.

example

parameter<uint32> maxNrInh := max(City/NrInhabitants); result = 550
parameter<uint32> maxCity  := max(City/CityName)     ; result = ‘Utrecht’

attribute<uint32> maxNrInhRegion    (Region) := max(City/NrInhabitants, City/Region_rel);
attribute<uint32> maxCityNameRegion (Region) := max(City/CityName, City/Region_rel);
City/NrInhabitants City/CityName City/Region_rel
550 Amsterdam 0
525 Rotterdam 1
300 Utrecht 2
500 DenHaag 1
200 Eindhoven 3
175 Haarlem null
null null 3

domain City, nr of rows = 7

maxNrInhRegion maxCityNameRegion
550 Amsterdam
525 Rotterdam
300 Utrecht
200 Eindhoven
0  

domain Region, nr of rows = 5

see also