fn:distinct-values function

Syntax

sequence-expression

A sequence of atomic values, or the empty sequence. The items in the sequence can have any of the following types:

• Numeric
• String
• Date or time types

Returned value

If sequence-expression is not the empty sequence, the returned value is a sequence that contains xs:string values that are the distinct values in sequence-expression. Two items are distinct if they are not equal to each other. XQuery uses the following rules to obtain a sequence of distinct values:

• If two values cannot be compared, those values are considered to be distinct.
• Values of type xs:untypedAtomic are compared using the rules for xs:string types.
• The order in which the sequence of values is returned might not be the same as the input order.
• The first value of a set of values that compare equal is returned.
• If sequence-expression is the empty sequence, the empty sequence is returned.
• For xs:double values, positive zero is equal to negative zero.
• If sequence-expression contains multiple NaN values, a single NaN value is returned.

Example

The following example returns the distinct values of node b:

SELECT XMLSERIALIZE(                                      
 XMLQUERY ('declare default element namespace            
 "http://posample.org";                                    
 fn:distinct-values($d/x/b)'  PASSING XMLPARSE(DOCUMENT   
 '<x xmlns="http://posample.org">
 <b>1</b><b>a</b><b>1.0</b><b>A</b><b>1</b></x>')
 AS "d")                                                  
 AS CLOB(1K) EXCLUDING XMLDECLARATION)                     
 FROM SYSIBM.SYSDUMMY1                                   

The returned value is ("1", "a", "1.0", "A").