Re: character equality under collation should not be used to test uniqueness
Posted by: Peter Gulutzan
Date: May 15, 2006 12:05PM

From the ANSI/ISO standard document:
Section 3.1 "Definitions":
"3.1.6.8 distinct (of a pair of comparable values): Capable of being distinguished within a given context.
Informally, not equal, not both null. A null value and a non-null value are distinct.
For two non-null values, the following rules apply:
— Two values of predefined type or reference type are distinct if and only if they are not equal."
"
3.1.6.12 equal (of a pair of comparable values): Yielding True if passed as arguments in a <comparison
predicate> in which the <comp op> is <equals operator>. (see Subclause 8.2, “<comparison predicate>”).

As for Oracle:
The section "Linguistic sorting and string
searching" mentions that DISTINCT will
"honor NLS_SORT" if NLS_COMP is LINGUISTIC.

https://dpt-info.u-strasbg.fr/doc/oracle/server.102/b14225/ch5lingsort.htm

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