a- describe what weak entity types are and how you can identify them in the Conceptual Data Model (CDM).
b- describe the differences between the XML data model and the relational data model.
c- Referring to your course learning materials and the e-library and/or other references, compare the following approaches to define XML documents: DTD, XML Schema, Relax NG and Schematron.
d- describe what ODBC is and why it is needed.