The fn:deep-equal function
compares two sequences to determine whether they meet the requirements
for deep equality.
Syntax
>>-fn:deep-equal(sequence-1,sequence-2)------------------------><
- sequence-1, sequence-2
- The sequences that are to be compared. The items in each sequence
can be atomic values of any type, or nodes.
Returned value
The returned value is the
xs:boolean value true if sequence-1 and sequence-2 have
deep equality. Otherwise the returned value is false.
If sequence-1 and sequence-2 are
the empty sequence, they have deep equality.
If two sequences
are not empty, the two sequences have deep equality if they satisfy
both of the following conditions:
- The number of items in sequence-1 is equal to the number
of items in sequence-2.
- Each item in sequence-1 (item-1) satisfies
the conditions for deep equality to the corresponding item in sequence-2 (item-2). item-1 and item-2 have
deep equality if they satisfy either of the following conditions:
- item-1 and item-2 are both
atomic values and satisfy either of the following conditions:
- The expression item-1 eq item-2 returns
true
- Both item-1 and item-2 have
the type xs:float or xs:double and the value NaN.
- item-1 and item-2 are both
nodes of the same kind and satisfy the conditions for deep equality
in the following table.
Table 1. Deep equality for nodes in a
sequence| Node kind of both item-1 and item-2 |
Conditions for deep equality |
|---|
| Document |
The sequence of the text and element children
of item-1 is deep-equal to the sequence of the text and element children
of item-2. |
| Element |
All of the following conditions must be true:- item-1 and item-2 have the
same name, which means that their namespace URIs match and their local
names match. Namespace prefixes are ignored. Name matching is done
using a binary comparison.
- item-1 and item-2 have the
same number of attributes, and every attribute of item-1 is
deep-equal to an attribute of item-2.
- One of the following conditions is true:
- Both nodes are either unvalidated or validated with a type that
permits mixed content (both text and child elements), and the sequence
of the text and element children of item-1 is deep-equal
to the sequence of the text and element children of item-2.
- Both nodes are validated with a simple type (such as xs:decimal)
or a type that has simple content (such as a "temperature"
type whose content is xs:decimal), and the typed value of item-1 is
deep-equal to the typed value of item-2.
- Both nodes are validated with a type that permits no content (neither
text nor child elements).
- Both nodes are validated with a type that permits only child elements
(no text), and each child element of item-1 is
deep-equal to the corresponding child element of item-2.
|
| Attribute |
All of the following conditions must be true:- item-1 and item-2 have the
same name, which means that their namespace URIs match and their local
names match. Namespace prefixes are ignored. Name matching is done
using a binary comparison.
- The typed value of item-1 is deep-equal to
the typed value of item-2.
|
| Text |
The content property values are equal when compared
as strings with the eq operator using the default
collation. |
| Comment |
The content property values are equal when compared
as strings with the eq operator using the default
collation. |
| Processing instruction |
All of the following conditions must be true:- item-1 and item-2 have the
same name.
- The content property values are equal when compared as strings
with the eq operator using the default collation.
|
Example
The following function compares
the sequences (1,'ABC') and (1,'ABCD') for deep equality. String comparisons
use the default correlation.
fn:deep-equal((1,'ABC'), (1,'ABCD'))
The
returned value is false.
DB2 Version 9.7 for Linux, UNIX, and Windows