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
- Domain of the arguments must match or be void (literals or parameters can be compared to data items of any domain).
- 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