Invert

relational-functions invert

syntax

  • invert(relation)

definition

invert(a) inverts the relation argument.

Inverting means the resulting attribute has as domain-unit the values-unit and as values unit the domain unit of the relation argument.

applies to

  • attribute relation with value-type of the group CanBeDomainUnit

example

attribute<Region> invertRegion_rel (Region) := invert(City/Region_rel);
City/Region_rel
0
1
2
1
3
null
3

domain City, nr of rows = 7

InvertRegion_rel
1
4
3
7
null

domain Region, nr of rows = 5