This assignment must be in the APA format. chapter 3 The Relational Data Model and Relational Database Constraints 3.2. Why are tuples in a relation not ordered? 3.3. Why are duplicate tuples not allowed in a relation? 3.5. Why do we designate one of the candidate keys of a relation to be the primary key? chapter 4 Basic SQL 4.2. List the data types that are allowed for SQL attributes. 4.4. Describe the four clauses in the syntax of a simple SQL retrieval query. Show what type of constructs can be specified in each of the clauses. Which are required and which are optional?