Material Didáctico. Bases de Datos. Otoño MC David Eduardo Pinto Avendaño

Transcription

1 BENEMÉRITA UNIVERSIDAD AUTÓNOMA DE PUEBLA FACULTAD DE CIENCIAS DE LA COMPUTACIÓN Material Didáctico Bases de Datos Otoño 2002 MC David Eduardo Pinto Avendaño

2 1 Benemérita Universidad Autónoma de Puebla Facultad de Ciencias de la Computación Basic Knowledge Development of DataBase Schemas MC. David Eduardo Pinto Avendaño 2 Agenda 1. Introduction 2. Overview of database development 3. Modeling basic entities 4. Modeling relationships 5. Adding detail to the diagram 6. Unique Identifiers 7. Resolving many to many relationships Day 1 3 Agenda 8. Modeling hierarchies, networks and roles 9. Modeling complex structures 10. Conceptual modeling review 11. Initial database design 12. Mapping exclusive relationships and entities to tables 13. Normalization Day 2

3 4 Introductions 5 Development Approach TECHNIQUES METHODS TOOLS 6 CDM Development Approach Business Requirement Definition Existing System Examination Technical Architecture Database Design and Build Module Design and Build Data Conversion Documentation Testing Training Transition Post System Support

4 7 Database Development Process ER model, entity definition Table, index, view Inmation Conceptual Data Modeling Database Design Database Build Database Business Requirements Cross-checking Cross-checking Operational System Process Function Modeling Application Design Application Build Application Function hierarchy, function definition Module (screen, report, menu, SQL) 8 Database Development Process CONCEPTUAL LOGICAL PHYSICAL Table Definitions Database ERM 9 Terminology CONCEPTUAL LOGICAL (Business view) (Systems view ) ANALYSIS ENTITY RELATIONSHIP ATTRIBUTE UNIQUE IDENTIFIER DESIGN TABLE FOREIGN KEY COLUMN PRIMARY KEY UNIQUE KEY

5 10 Business Inmation Requirements I manage thehuman Resources Department a large company. We need to keep inmation about each of our company s employees. We need to track each employee s first, last, job or position, hire date and salary. For any employees on commission, we also need to track their potential commission. Each employee is assigned a unique employee number. Our company is divided into departments. Each employee is assigned to a department, example, accounting, sales or development. We need to know the department responsible each employee and the department s location. Each department has a unique number, example, accounting is 10 and sales is30. Some of the employees are managers. We need to knoweach employee s manager and the employees that each manager manages. 11 Entity Definitions An object of interest to the business A class or category of thing A d thing A noun A thing of significance about which the business needs inmation 12 Attribute Definitions Nouns used to describe entities Specific pieces of inmation which need tobe known An entity should have attributes

6 13 Diagramming Entities (CLIENT) Soft box Singular, unique inuppercase Optional synonym Attribute s inlower case MEMBERSHIP DEPARTMENT EMPLOYEE date of birth 14 Entity Instances EMPLOYEE Head office Personnel Finance Sales DEPARTMENT 15 Identifying a Unique Instance EMPLOYEE badge number date of birth salary

7 16 Identify and Model Entities Identify anoun Is it significant? Is there inmation about it that the business needs to keep? Is it a group or an instance? Name the entity Write adescription of it Identify a few attributes Draw a soft box it 17 In Class Exercise - Solution I am the manager of a training company that provides instructor-led COURSEs in management techniques. We teach courses, each of which has a code, a, and a fee. Introduction to UNIX and C Programming aretwo of our more popular courses. Courses vary in length from one to four days. Paul Rogers and Maria Gonzales aretwo of our best teachers. We need each INSTRUCTOR s and phone number. The STUDENTs can take several courses over time, and many do this. Jamie Brown from AT&T took every course we offer! We like to have each student s and phone number. 18 In Class Exercise - Solution COURSE code fee length INSTRUCTOR phone no. STUDENT phone no

8 19 Relationship Definitions The way one entity relates to another The business rules that link together business inmation needs What one thing has to dowith another A d association between entities 20 Bi-directional Relationships DMDD COURSE SMT COURSE INSTRUCTOR COURSE 21 Diagramming Conventions A line between two entities Lower case relationship Optionality (Minimum cardinality) Mandatory - must be Optional - may be Degree (Maximum cardinality) One or more One and only one

9 22 Diagramming Conventions COPY many (crow s foot) mandatory optional one TITLE 23 Relationship Syntax Each must be one or more relationship entity 1 or or entity 2 may be one and only one Subject entity Optionality Name Degree Object entity 24 Validation - in class solution assigned to EMPLOYEE DEPARTMENT responsible Each EMPLOYEE must be assigned to one and only one DEPARTMENT Each DEPARTMENT may be responsible one or more EMPLOYEES

10 25 Relationship Types Many -to-one Many-to-Many One-to-One 26 Many -to-one Relationships CUSTOMER visited by assigned to SALES REPRESENTATIVE 27 Many-to-Many Relationships PATIENT attended by assigned to HEALTH CARE WORKER

11 28 One-to-One Relationships BICYCLE is ridden by CYCLIST the rider of Represents a snapshot in time 29 Analyzing and Modeling Relationships 1 Determine the existence ofa relationship 2 Name each direction of the relationship 3 Determine the degree of each direction of the relationship 4 Determine the optionality of each direction of the relationship 5 Read the relationship aloud to validate it 30 Attributes Badge Number - Identifies an employee Name - Qualifies an employee Payroll category (weekly or salaried) - Classifies an employee Date of birth - Quantifies an employee Employment status (active, leave, terminated) - Expresses the status of an employee

12 31 Finding Attributes Is this attribute really needed? Beware of obsolete requirements from previous systems Beware of derived data 32 Attribute Diagramming Conventions badge num first last payroll num EMPLOYEE date of birth employment status Inside the entity's soft box Singular Lowercase 33 Meaningful Components PERSON ITEM code Break down aggregate attributes PERSON last first ITEM type vendor num

13 34 Verify Single Value RENTAL transaction date total amount paid item Yes, more than one item may berented at a time. An entity is missing. RENTAL ITEM item num Can an attribute have more than one value an instance of the entity? RENTAL transaction date total amount paid 35 Attributes Which have Attributes TITLE product code title description review details REVIEW author comment date recorded Does inmation need to be stored about any of the attributes? Yes, review details. An entity is missing. TITLE product code title description 36 Finding Common or Derived Data Count Total Maximum, Minimum, Average Calculation Derived attributes are redundant and canlead to inconsistent values

14 37 Attribute Optionality Mandatory Attributes A value mustbe stored each entity instance Tagged with Optional Attributes A value may be stored each entity instance Tagged with o 38 Attribute Optionality o EMPLOYEE badge num first last title o weight 39 Attribute Details and Volumes Attribute - Engine Size Format Type Number Maximum length 4 Average length 4 Decimal place 1 Unit of measure cc Allowable values 900,1000,1500,1800,2000 Volume Initial 100%

15 40 Unique Identifier Definition Each entity instance must be able to be uniquely identified A combination of attributes or relationships that serve to identify a specific instance of an entity. 41 Simple Unique Identifier 342 CUSTOMER # customer num Single attribute Tag the UID with # Compound UID - Attributes MEMBERSHIP # num # ostart date Multiple attributes

16 43 Compound UID - Composite ACCOUNT num BANK # num What would you need to know to identify a specific instance of ACCOUNT? 44 Compound UID - Composite ACCOUNT # num Use # to indicate that the attribute is part of the entity s UID BANK # num Use a UID bar to indicate that a relationship is part of the entity s UID 45 Compound UID - Relationships RENTAL RENTAL ITEM rental period o return date # transaction num transaction date COPY # inventory num purchase cost What do you need to know to identify a specific instance of RENTAL ITEM?

17 46 Compound UID - Relationships RENTAL RENTAL ITEM rental period o return date # transaction num transaction date COPY # inventory num purchase cost Rental item requires the rental transaction num and the inventory num 47 Multi-Level Relationship UIDs TICKET seat number CUSTOMER # PERFORMANCE PLAY VENUE # date # time # title # What would you need to know to identify a specific instance of TICKET? 48 Multiple UIDs badge num payroll num first and last # (1) EMPLOYEE badge num #(2) o first #(2) o last # (3) payroll num

18 49 Identifying the Problem From this diagram, can you tell which supplier instance provides Casablanca? TITLE # prod code supplied by supplier of SUPPLIER # supplier no In which entity would you store the attribute purchase price? 50 Intersection Entities availableas TITLE TITLE # prod code CATALOG ITEM purchase price supplier of SUPPLIER # supplier no 51 Unique Identifiers available as TITLE # TITLE prod code CATALOG ITEM purchase price supplier of SUPPLIER # supplier no OR available as TITLE # TITLE prod code CATALOG ITEM # item num purchase price supplier of SUPPLIER # supplier no

19 52 Modeling Recursive Relationships...he s my manager...and mine... but I m HIS manager! manager of EMPLOYEE managed by 53 Modeling Hierarchical Data Company Division Department Team TEAM # DEPARTMENT # DIVISION # # 54 Hierarchies as Recursive Relationships TEAM # DEPARTMENT # DIVISION # # made up of ORGANIZATION ELEMENT # type within

20 55 Network Structures a part of COMPONENT # identifier made upof 56 Network Structures ASSEMBLY RULE o quantity made up of COMPONENT # identifier a part of 57 Exclusive Entities MOVIE category duration O audio TITLE # product code title description GAME category medium minimum memory

21 58 Exclusive Entities COPY inventory num o condition MEMBERSHIP # num start date expiry date o termination acquired from held by the source of the holder of # id telephone num o supplier num o sales contact 59 Splitting Entities COPY inventory num o condition MEMBERSHIP # num start date expiry date o termination acquired from held by the source of the holder of # id telephone num SUPPLIER supplier num sales contact OTHER 60 Nesting Entities CAR driven by authorized to drive SALES REP TELESALES EMPLOYEE CLERICAL HUMAN RESOURCES

22 61 Recursive Subtypes ORGANIZATION ELEMENT (ORGANIZATION) DEPARTMENT (SUBDIVISION) of within made up of the classification ORGANIZATION ELEMENT TYPE 62 Modeling Exclusive Relationships MEMBERSHIP num startdate expiry date o termination held by o o held by the holder of the holder of postal area 0 contact CUSTOMER num first last 63 Modeling Exclusivity We offer membership to individual customers and companies CUSTOMER MEMBERSHIP MEMBER CUSTOMER MEMBERSHIP MEMBERSHIP INDIVIDUAL ORGANIZATION CUSTOMER

23 64 Modeling Data over Time What if you need to hold an apartment s rental history? APARTMENT # code address rented by the renter of PERSON # id last first 65 Modeling Data over Time RENTAL HISTORY # from date o to date APARTMENT # code address rented by the renter of PERSON # id last first 66 Modeling Data over Time MEMBER # id last first employed by the employer of # code

24 67 Modeling Data over Time employed by MEMBER # id last first EMPLOYMENT HISTORY ENTRY # from date o to date the employer of # code 68 Fan Traps PERSON employed by # id last first the employer of the holder of # code heldby the POSITION # job title o job description employer of included in 69 Fan Traps PERSON employed as # id last first employed at HISTORY startdate o end date the employer POSITION HISTORY start date o end date # code held by the employer POSITION ORGANIZATION HISTORY start date o end date # job title o job description the subject of

25 70 Transferable Relationships PERSON # id last first works in employs DEPARTMENT # code Head office Personnel Finance Sales 71 Non-Transferable Relationships COPY inventory num o condition acquired from the source of # id telephone num SUPPLIER supplier num sales contact OTHER 72 Design of Database schema CONCEPTUAL LOGICAL (Business view ) (Systems view ) ANALYSIS ENTITY RELATIONSHIP ATTRIBUTE UNIQUE IDENTIFIER DESIGN TABLE FOREIGN KEY COLUMN PRIMARY KEY UNIQUE KEY

26 73 Creating the Outline Design 1 Map simpleentities to tables 2 Map attributes to columns, and document sample data 3 Map unique identifiers to primary keys 4 Map relationships to eign keys 74 Mapping Simple Entities EMPLOYEE #(1) (2) # (3) o (3) # badge num payroll num first last o position Column Key type Nulls Sample data Table Name: BADGE_ NUM PAYROLL_ NUM EMPLOYEES FIRST_ NAME LAST_ NAME PK UK1 UK2 UK2 NN NN NN POSITION 75 Mapping Relationships - M:1 EMPLOYEE #(1) (2) # (3) o (3) # DEPARTMENT # badge num payroll num first last o position num Column Key type Nulls Sample data Table Name: BADGE_ NUM PAYROLL_ NUM EMPLOYEES FIRST_ NAME LAST_ NAME PK UK1 UK2 UK2 NN NN NN POSITION DEP_ NUM FK NN

27 76 # BICYCLE # id type CYCLIST num Mapping Relationships - Mandatory 1:1 Column Key type Nulls Sample data ID TYPE CYCLIST _ NUM PK FK, UK NN NN NN Table Name: BICYCLES 77 Mapping Relationships - Optional 1:1 # BICYCLE # id type CYCLIST num OR Column Key type Nulls Sample data Column Key type Nulls Sample data ID PK NN NUMBER PK NN TYPE NN NAME NN CYCLIST _NUM FK, UK BICYCLE _ID FK, UK Table Name : BICYCLES Table Name: CYCLISTS 78 the manager of EMPLOYEE (1) # (2) # (3) # o (3) # badge num payroll num first last o position Mapping Relationships - Recursive 1:M mana ged by Column Key type Nulls Sample data Table Name: EMPLOYEES BADGE_ NUM PAYROLL_ NUM FIRST_ NAME LAST_ NAME PK UK1 UK2 UK2 NN NN NN POSITION EMP_ MAN_ NUM FK NN

28 79 # id Mapping Relationships - Recursive 1:1 the spouse of PERSON_ Column ID NAME SPOUSE PERSON _ID Table Name: PERSONS married to Key type PK FK,UK Nulls NN NN Sample 2345 ANN 6785 data 6785 RAY Mapping Arcs OFFICE SUITE # building id # suite no o o o # # # INDIVIDUAL id PARTNERSHIP code num 81 Mapping Subtypes TITLE # product code MOVIE category GAME medium Single table design Multiple table design Arc implementation

29 82 Explicit Arc Design Table Name: OFFICE_SUITES Column Key type Nulls NN NN Sample data OFFICE SUITE # buildingid # suite no BUILDING SUITE COMP_ IND_ID PART_CODE _ID _NO NUM PK PK FK1 FK2 FK A o o o # INDIVIDUAL id # PARTNERSHIP code # num Generic Arc Design Table Name: OFFICE_SUITES Column BUILDING _ID SUITE _NO RENTER_ID Key type PK PK FK NN NN NN Nulls Sample data OFFICESUITE # building id # suite no A o o o INDIVIDUAL # id # PARTNERSHIP code # number RENTER_TYPE NN I P I C! 84 Single Table Design MOVIE TITLE # product code GAME category medium Column PRODUCT _CODE Key type PK Nulls NN Sample data TYPE NN MOVIE_ CATEGORY M 453 HORR 516 G CD 677 M DRAMA Table Name : GAME_ MEDIUM 444 G CASS TITLES

30 85 Multiple Table Design Table Name: MOVIES Column PRODUCT _CODE Key type Nulls Sample data PK NN MOVIE TITLE # product code GAME category medium MOVIE_ CATEGORY NN 453 HORR 677 DRAMA Column PRODUCT _CODE Key type Nulls Sample data NN PK Table Name: GAMES GAME_ MEDIUM NN 516 CD 444 CASS 86 Specify Referential Integrity DEPARTMENT DEPT 40 DEPT 40 FRED JOE BILL FRED JOE BILL EMPLOYEE RULE RESTRICT CASCADE 87 Specify Referential Integrity DEPARTMENT DEPT 40 DEPT 40 DEPT FRED JOE BILL FRED JOE BILL EMPLOYEE RULE NULLIFY DEFAULT

31 88 Outline Index Design ADAMS DATA BLOCKS ALLEN SMITH BLAKE BLAKE ALLEN JAMES WARD CLARK FORD JONES JAMES MARTIN KING JONES BLAKE CLARK SCOTT KING MILLER MARTIN KING TURNER MILLER SCOTT TURNER ADAMS SMITH INDEX BLOCKS JAMES FORD TURNER MILLER WARD 89 Establish Views CUS_ NO CUS_ LNME CUS_ FNME ORD -NUM ORD -DTE ORD_ CUS_NO 90 Consider Derived Data Order 1234 item item item item item total 39.96

32 91 Artificial Keys CUSTOMER # o first # last # address CUSTOMER # code first last address 92 Planning Physical Storage Estimate the amount of disk space needed Decide on placement Definestorage allocation 93 ER Diagrams and Normalization ER Diagramming Top down approach Fast Examine requirements Business knowledge Normalization Bottom up approach Very slow Examine existing data Mathematically based Top down create - bottom up checking Accuracy Greater understanding of the data

33 94 Rules of Normalization Collect and list the raw data 0NF Remove repeating groups 1NF Remove part key dependencies 2NF Remove inter -data dependencies 3NF Remove inter -key dependencies BC NF Test and identify transitive dependencies Optimize Retest Draw and use the model 95 Collect the Raw Data customer John Doe order John Doe order product A453 desc. Bowls quantity 6 address anytown any place date 03/04/96 0NF # customer order num product num product description quantity ordered customer address dateordered 0NF 1NF 2NF 3NF BC NF Test Optimize Retest 96 Remove Repeating Groups 0NF # customer order num product num product description quantity ordered customer address date ordered 1NF # customer customer address # customer FK # order num product num product description quantity ordered dateordered 0NF 1NF 2NF 3NF BC NF Test Optimize Retest

34 97 Remove Part Key Dependencies 1NF # customer customer address # customer FK # order num product num product description quantity ordered dateordered NO CHANGE 2NF # customer customer address # customer # order num FK FK # order num product num product description quantity ordered date ordered 0NF 1NF 2NF 3NF BC NF Test Optimize Retest 98 Remove Inter-Data Dependencies 2NF # customer customer address # customer # order num FK FK # order num product num product description quantity ordered date ordered NO CHANGE NO CHANGE 3NF # customer customer address # customer # order num FK FK # order num product num FK quantity ordered date ordered # product num product description 0NF 1NF 2NF 3NF BC NF Test Optimize Retest 99 Remove Inter-Key Dependencies 3NF # customer customer address # customer # order num FK FK # order num product num FK quantity ordered NO CHANGE date ordered # product num product description NO CHANGE NO CHANGE BCNF # customer customer address # order num customer FK FK # order num product num quantity ordered date ordered # product num product description 0NF 1NF 2NF 3NF BC NF Test Optimize Retest

35 100 Optimize BCNF # customer num customer BCNF # customer customer address # order num customer FK # order num product num FK quantity ordered date ordered Transitive OPTIMIZED DATA GROUPS # customer num customer customer address # order num product num FK customer num FK quantity ordered date ordered 0NF 1NF 2NF 3NF BC NF Test Optimize Retest 101 Entities and Normalization # # EMPLOYEE badge num payroll num first last payroll category date of birth employmentstatus previous departments Does any attribute have more than one value? Does any attribute need just part of the UID? Is any attribute dependent on another attribute and not the UID? Does any part of theuid depend on another part of the UID? 102 Summary CONCEPTUAL LOGICAL PHYSICAL Table Definitions Database ERM