CS 3630 Database Design and Implementation

Design Methodology Three main phases A structured approach that uses procedures, techniques, tools, and documentation aids to support and facilitate the process of design. Three main phases Conceptual database design Understanding client data E-R (EER) Model Agreement between clients and designers E-R Model could be used for any database system Logical database design Mapping E-R Model to (relational) database schema Normalization Physical database design 2013: Finished at 43 for both sections

Mapping E-R Model to Relational Database Schema Entity type  Table schema How to maintain relationships?

Mapping Strong Entities to Relation (Table) Schemas Replacing composite attributes with simple attributes Adding new tables to remove multi-value attributes

Replacing Composite Attributes with Simple Attributes Name: Composite (FirstName, LastName) Use two attributes: FirstName LastName Address : Composite (Street, City, State, Zipcode) Use four attributes: Street City State Zipcode Performance issue

Composite Attributes Search/Project on state or zip code staffNo Name Address . . . SL21 John White 1 main street, Platteville, WI 53818 SG37 Ann Beech 15 University Dr, Madison, WI 53706 SA9 Mary Howe 908 Western avenue, Dubuque, IA 52001-1234 Search/Project on state or zip code

Simple Attributes Search/Project on state or zip code staffNo firstName lastName Street City State zip SL21 John White 1 main street Platteville WI 53818 SG37 Ann Beech 15 University Dr Madison 53706 SA9 Mary Howe 908 Western avenue Dubuque IA 52001-1234 Search/Project on state or zip code

E-R Model Staff StaffNo Name: Simple or Composite? Address Salary . . .

Removing Multi-Value Attributes No multi-value attributes in relational databases First Order Logic No sets as set elements

Multi-Value Attributes branchNo street city state zipCode telNo B001 1 main street Platteville WI 53818 608-348-1234 608-348-3345 B002 15 university drive Madison 53706 608-255-3034 608-255-1023 877-323-5678 …

Removing Multi-Value Attributes without Losing Data Entity Type in E-R Model Branch branchNo . . . telNo: multi-value How to Store telNo? phoneOne phoneTwo phoneThree (When we know the limit of phone numbers at a branch: at most three) Staff staffNo homePhone workPhone cellPhone

Each Branch Has at Most Three Phone Numbers branchNo street . . . phone1 phone2 phone3 B001 1 main street 608-348-1234 608-348-3345 B002 15 university drive 608-255-3034 608-255-1023 877-323-5678 …

Home Phone, WorkPhone and Cell Phone staffNo street . . . homePhone workPhone cellPhone SL21 1 main street 608-348-1234 608-348-3345 SG37 15 university drive 608-255-1023 877-323-5678 SA79 … 608-255-3034 608-255-3847

Multi-Value Attributes Without Limit Entity Type in E-R Model Branch branchNo . . . telNo: multi-value (NO LIMIT or LIMIT TOO LARGE) More Examples Student Major Work Experience Research publications . . .

Replacing Multi-Value Attributes branchNo Street City State zipCode B001 B002 … branchNo . . . telNo B001 608-348-1234 608-348-3345 B002 608-255-3034 608-255-1023 877-323-5678 … branchNo telNo B001 608-348-1234 608-348-3345 B002 608-255-3034 608-255-1023 877-323-5678 … One table  two tables Multi-Value attribute  multiple records Primary Key  Foreign Key

Replacing Multi-Value Attributes Entity Type in E-R Model Branch branchNo . . . telNo: multi-value (NO LIMIT!) How to Store telNo? Remove it from Branch and create a new table! BranchPhone telPhone Which attributes should be in the new table? The PK attribute(s) and the multi-value attribute. Is branchNo the PK in Branch? Is branchNo the PK in BranchPhone? Foreign Key!

Primary Key and Foreign Key branchNo telNo B001 608-348-1234 608-348-3345 B002 608-255-3034 608-255-1023 877-323-5678 … branchNo Street City State zipCode B001 B002 …

What is the Primary Key? BranchPhone branchNo telPhone Assumption Two branches don’t share the same phone # Two branch can shared the same phone # (branchNo, telephone) newAtt Must be unique!

Replacing Multi-Value Attributes Always use a new table to replace any multi-value attribute IN Assignments Quizzes Tests Final

Mapping Entity Type to Table Schema Entity Type in E-R Model Branch branchNo address: composite (street, city, state, zipCode) telNo: multi-value (with or without limit!) Table Schema (DBDL) Branch (branchNo, street, city, state, zipCode) PK: branchNo AK: street, city, state, zipCode FK: NONE BranchPhone (newAtt, branchNo, telPhone) PK: newAtt AK: NONE FK: branchNo references Branch

Mapping Entity Type to Table Schema Entity Type in E-R Model Staff staffNo . . . DOB workExperince: multi-value Composite (start, end, org, position) Store workExperince with staffNo in a new Table! WorkExperience start end org position PK? Could create a new PK attribute (workExpID) FK?

Storing Work Experience Entity Type in E-R Model Staff staffNo . . . DOB workExperince: multi-value Composite (start, end, org, position) Table Schema (DBDL) Staff (staffNo, . . ., DOB) PK: staffNo AK: NONE FK: NONE WorkExperience(workExpID, staffNo, start, end, org, position) PK: workExpID AK: None FK: staffNo references Staff

Individual Assignment Due Wednesday, Feb 22