Eq_or_both_null

ordering-functions equals or both values null

syntax

  • eq_or_both_null(a, b)

definition

eq_or_both_null(a, b) results in a boolean data-item indicating if the values of data item a are equal to the corresponding values of data item b or if both corresponding values are null.

description

The comparison between two missing values (null == null) results in the value True.

applies to

Data items with Numeric, Point, string or bool value-type

conditions

  1. domain-unit of the argument must match or be void (literals or parameter can be compared to data items of any domain).
  2. Arguments must have matching:

example

attribute<bool> AisB (CDomain) := eq_or_both_null(A, B);
A B AisB
0 0 True
1 2 False
2.5 2.5 True
-100 100 False
999 -999 False
null 0 False
null null True
0 null False
null 100 False
100 null False

CDomain, nr of rows = 10

see also