When you specify XML queries with character literals that contain the XML special characters, you can write them as either plain characters or as pre-defined entities. The following example shows two points:
The XML document contains an element "<a>" whose value is the XML special characters &<>", represented by their predefined entities, &<>"
The XML query specifies a character literal with those same XML special characters, also represented by their predefined entities.
select xmlextract('/a="&<>""',
"<a>&<>"</a>")
----------------------------------
<a>&<>"</a>
The following example is the same, except that the XML query specifies the character literal with the plain XML special characters. Those XML special characters are replaced by the predefined entities before the query is evaluated.
select xmlextract("/a='&<>""' " ,
"<a>&<>"</a>")
----------------------------------
<a>&<>"</a>
