Databases Tutorial. January 19,2012 Jing Chen Mcmaster University

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1 Databases Tutorial January 19,2012 Jing Chen Mcmaster University

2 Info Office: ITB Homepage:

3 Outline (to be continued ) Review -Entity Set, Relationship Set, Attributes -Cardinality Constraints, Participation Constraints -Primary Key, Weak Entity Sets -Specialization Example How to log onto db2 server

4 Entity Sets An entity is an object that exists and is distinguishable from other objects. An entity set is a set of entities of the same type that share the same properties. E-R Notation Rectangle Account

5 Relationship Sets A relationship is an association among several entities. A relationship set is a set of relationships of the same type. E-R Notation Diamonds depositor Account

6 Attributes (to be continued ) Attributes is a set of descriptive properties possessed by all members of an entity set. E-R Notation Ellipse customer_name access_date customer_id customer_tel account_number balance depositor Account

7 Attributes (to be continued ) Simple and composite attributes middle_name first_name last_name customer_name customer_name customer_id customer_tel customer_id customer_tel

8 Attributes Single and multi-valued attributes customer_name customer_name customer_id customer_tel customer_id customer_tel

9 One-to-many Cardinality Constraints (to be continued ) depositor Account One-to-one depositor Account

10 Cardinality Constraints Many-to-many depositor Account Role indicator employee manager worker Works_for

11 Participation Constraints Partial participation depositor Account Total participation depositor Account

12 Key Superkey -{customer_id} or -{customer_id,customer_name} or -{customer_id,customer_name,customer_tel} Candidate key -{customer_id} Primary key -{customer_id} customer_name customer_id customer_tel

13 Weak Entity Sets load_id amount date payment_id amount Loan for loan payment Identifying entity set Identifying relationship weak entity set

14 Specialization (to be continued ) Overlapping person_id name Telephone Person salary ISA credit_rating employee customer

15 Specialization disjoint account ISA disjoint Saving account Checking account

16 Examples (to be continued ) Our company arranges rentals of properties owned by both private and business owners. We assign every property owner a unique owner number for identification, we record its address (consisting of a street, street number, town or city, and province), the owner s name (consisting of first, middle, and last name for a person or name of a business), and the owner s addresses and the owner s phone numbers. For a business owner, we record type (description) of its business. Modified from assignment 1 of 2011

17 Example (to be continued ) E-R model Modified from assignment 1 of 2011

18 Example (to be continued ) Each property is identified by a unique property number, we record its address and its type. Each property may be placed in several advertisements. Each such advertisement may be displayed in many newspapers on several dates. The newspapers are identified by unique names Modified from assignment 1 of 2011

19 Modified from assignment 1 of 2011

20 Reference Databases system concepts, fifth edition, Authored by Abraham Silberschatz, Henry F.Korth, S.Sudarshan Databases Tutorial, Authored by Chia-Chun (Jasper) Weng, Mei Jiang, Mcmaster University, Jan,19,2011

Design Process Modeling Constraints E-R Diagram Design Issues Weak Entity Sets Extended E-R Features Design of the Bank Database Reduction to

Design Process Modeling Constraints E-R Diagram Design Issues Weak Entity Sets Extended E-R Features Design of the Bank Database Reduction to Relation Schemas Database Design UML A database can be modeled