CSCI 5333 Data Base Management System

Spring 2002 (1/14-5/6)

I. The Phases of Database Design (see Figure 3.1): 

1. Data: requirements collection & analysis, conceptual design, logical design, physical design.
2. Operation: functional analysis, application program design, transaction implementation.
   

A. The DBMS-Independent Phases:

B. The DBMS-Dependent Phases:

Question: What phases are DBMS-independent?  What phases are DBMS-dependent?

Question: Which phase is the end of the DBMS-independent phases?  Which is the start of the DBMS-dependent phase?

Question: What is the relationship between the two threads (functional vs database)?

Question: Where does ER modeling fit in the phases?

Question: Where does the relational data model fit in the phases?

Question: At which phase does a database designer specify the database operations?

Question: Why does the 'physical design' phase take both the logical schema and the high-level transaction specification as the input?

Question: Why does the 'transaction implementation' phase take both the application program design and the internal schema as the input?

Ø Go to the Index

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II. Entity-Relationship Modeling

A. Terminology

concepts	definition	example
entity
entity type
entity set
attribute
simple (atomic) attribute
composite attribute
single-valued attribute
multivalued attribute
complex attribute
stored attributes
derived attributes
key attributes
P(V)
A: E --> P(V)
value sets (domains) V = P(V1) x P(V2) x ... x P(Vn)
relationship
relationship type
relationship set
relationship instance		Fig. 3.9 Fig. 3.10
role		Fig. 3.11
recursive relationship		Fig. 3.11
cardinality ratio
participation constraint
total (existence) participation
partial participation
structural constraint
attributes of relationship types
the weak (child, subordinate) entity types
the identifying (owner, parent, dominant) entity type
the identifying relationship
partial key

• Question: What makes a relationship different from an attribute?
• Question: How is a relationship between two entities represented in a relational model?  How if in an object-oriented database? HINT: See p.55.
• Question: It is said in the book that 'weak entity types' can sometimes be represented as complex attributes.  How?  What are the trade-offs of the alternative representations?  HINT: p.60.
  
• Exercise: Give a full interpretation of ALL the relationships existing in Figure 3.2.  Take into account 'cardinality ratio', 'weak relationships' and 'weak entities'.  
• Exercise: Compare Figure 3.2 and Figure 3.15.  Which one is more precise in expressing the relationships?
  

Ø Go to the Index

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