How do I implement composite key constraint for an xsd element I have. Basically I need to ensure that the two attributes (USERID and COURSEID) cannot be duplicated in the xml that I have.

How do I do that?

Aldwin Enriquez
"Dont you ever give up!"

__________________
\"Dont you ever give up!\"

I got it guys..I used xs:key element..

<xs:key name="unq_USER_COURSE">
  <xs:selector xpath="Courses"/>
  <xs:field xpath="@USERID"/>
  <xs:field xpath="@COURSEID"/>
</xs:key>

Aldwin Enriquez
"Dont you ever give up!"

Use an xsd:unique element with more than one xsd:field child; the combination of all the xsd:field's defines the composite key.

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference