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 of the arguments must match or be void (literals or parameters can be compared to data items of any domain).
2. Arguments must have matching:
   • value type
   • metric

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

• eq