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1869495 er diagrams

1869495 er diagrams






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    1869495 er diagrams 1869495 er diagrams Presentation Transcript

    • Database DesignVictor Matos 1
    • Phases of Database Design Data Requirements  Conceptual design begins with theSpecification of requirements and results collection of requirements and results Conceptual needed from the database (ER Diag.) Design  Logical schema is a description of the Conceptual Schema structure of the database (Relational, Logical Network, etc.) Design  Physical schema is a description of Logical Schema the implementation (programs, tables, Physical Design dictionaries, catalogs Physical Schema 2
    • Models A data model is a collection of objects that can be used to represent a set of data and operations to manipulate the data  Conceptual models are tools for representing reality at a very high-level of abstraction  Logical models are data descriptions that can be processed by computers 3
    • Conceptual model:Entity-Relationship Diagrams  Entities represent classes of real-world objects. Person, Students, Projects, Courses are entities of a University database  Relationships represent interactions between two or more entities N 1 Lives_In Person City Is_Born_In N 1 4
    • Example:  Every employee works in at least one project  Every project has employees working on it. EMPLOYEE N N PROJECT SSN WORKS_ON Name Name Code Salary 5
    • Higher-Order Relationships A relationship may involve more than two entities Course Meets Classroom Day 6
    • Recursive relationships Relationships could be mapped from one entity to itself Manager_Of 1 Employee Manages N Subordinate_To 7
    • Attributes Attributes represent elementary properties of the entities or relationships. The stored data will be kept as values of the attributes Lives_In N 1 CITY PERSON Moving_Date Name Ssn Country Name Birth_Date Profession Elevation Population Is_Born_In N 1 8
    • Generalizations• An entity could be seen from many different viewpoints• Each viewpoint defines a set of roles in a generalization• Example below uses SEX to classify the object “Person” PERSON Ssn Name Address MAN FEMALE Draft_Status Maiden_Name 9
    • Generalizations A classification could be disjoint or overlapping  An entity could have more than one classification PERSON Ssn Name Address SEX JOB Full_Time Part_Time MAN FEMALE Annual_Salary Hour_Rate Draft_Status Maiden_Name Department Weekly_Hours 10
    • Example: Department Store 1/2 A department store operates in several cities  In a city there is one headquarter coordinating the local operations  A city may have several stores  Stores hold any amount of items  Customers place their orders for any number of items to a given store GOAL: Optimize shopping in each city 11
    • Example: Department Store 2/2 STORES 1 CITIES Store ID N LOCATED City Name Address IN State Manager ID HeadQtr Address N N CUSTOMER Customer Name Address HOLD IN-CITIES Phone Number Qty Held Qty_in_cities N N 1 ITEMS Item ID N N ORDERS N ITEMS ORDERED Description Order Number PLACE Qty Ordered Size Order Date Color 12
    • Example: University Database  Professors work for only one department  Departments have many professors  Each course is taught by only one professor  Students make a plan or program of study  A course could meet in several rooms/times  Graduate students must have an advisor  Cities are categorized as resident/BirthPlace  Visiting prof. need an End/Start date 13
    • University Database CITY 1 N PERSON DEPARTMENT 1 Name BIRTH_PLACE LastName Name Belongs_To State Age Phone N N RESIDENT N PROFESSOR STUDENT TenureStatus Title N N 1 VISITING_ ENROLLED PLANNED N PROFESSOR GRADUATE_STUDENT ADVISED_BY Start_Appointment Semester Semester Grade End_Appointment N N COURSE N 1 Title TAUGHT_BY Description Semester Credits 1 TIME N N ROOM Day MEETS RoomNumber Hour Building University database 14
    • Soccer Database A team has players, one coach, fans  Teams play according to a schedule  Teams need to practice in a Stadium  Attendance and scores must be recorded 15
    • Soccer Database PERSON Ssn Name Address FAN PLAYER COACH Name Uniform_Size Personal Record Address Shoe_Size Years Experience Favorite Bar N N 1 PLAYS SUPPORTS MANAGES _FOR 1 1 N TEAM Name Location Phone N N N PRACTICES PLAY_ AGAINST N GAME STADIUM Number TAKES Name ATTENDS Attendance PLACE Address N N Final Score N AT 1 Capacity 16 Date
    • Research Project Database  Some employees are researchers  Every project has a leader investigator  Every project must be funded by an agency  A project may include several topics  A topic could appear in several projects  Researchers must produce report(s)  Each employee must have a supervisor 17
    • Contract-Supplies System 1/3 A company negotiates contracts with suppliers to provide certain amount of items at a fixed price  Orders are placed against any of the already negotiated contracts  A contract could provide items to any number of orders 19
    • Contract-Supplies System 2/3  An order may include any number of items negotiated in the contract  Orders should not exceed the maximum amount of items quoted in the contract  All items in an order must be provided as part of a single contract and a single project 20
    • Contract-Supplies System 3/3 SUPPLIERS Supplier Number Name Address 1 PROJECTS NEGOTIATE Project Number Date of Contract Project Data N 1 CONTRACTS 1 N Contract Number SUPPLIED AS Text NEEDED BY N TO SUPPLY N Contract Price Contract Amount N ORDERS ITEMS N N MADE OF Order Number Item Number Order QTY Date Required Description Date Completed 21
    • Manufacturing: Requisitions 1/3  Projects are broken into tasks  Tasks are assigned to departments  A task is created for one project and assigned to one department  Requisitions are made for projects  Each requisition could ask for any number of items 22
    • Manufacturing: Requisitions 2/3  Each requisition is for one project and is made to one supplier  Items could be: equipment or materials and are coded in a similar way  Suppliers send periodic price notices to advise the company of any changes in their prices 23
    • Manufacturing: Requisitions 3/3 PROJECTS 1 N TASKS Project Number MADE OF Task Number Project Data Task Data 1 1 REQUESTS FOR N N SUPPLIERS REQUISITION N 1 Supplier Item Number FROM Number Qty Requested Supplier Data N 1 CONTAINS SENDS N N ITEMS 1 N PRICE ADVICE Item Number CHANGES Price Item Data Effective Date MATERIAL ITEM EQUIPMENT ITEM Code Code Description Description Weight 24 Container
    • Job-Shop Accounting System 1/4  The system is used by a company that manufactures special-purpose assemblies for customers  To manufacture assemblies the company creates a sequence of processes (steps)  Each process is supervised by a department  Assume there are three type of processes: PAINT, FIT, CUT 25
    • Job-Shop Accounting System 2/4  During manufacturing an assembly could pass through any sequence of processes, in any order; it may pass through the same process more than once  A unique Job# is given to any new assembly.  Costs and started-terminated dates must be recorded 26
    • Job-Shop Accounting System 3/4  Anaccounting system is used to keep track expenditure for each:  DEPT,  PROCESS,  ASSEMBLY  Asa job proceeds, cost transactions can be recorded against it. 27
    • Job-Shop Accounting System 4/4 CUSTOMER ACCOUNTS S Account ID Customer ID Date Address Established A1 ASSEMBLY DEPT PROCESS ORDERS ACCOUNTS ACCOUNTS ACCOUNTS T1 Account 1 Account 2 Account 3 Details Details Details TRANSACTIONS T2 ASSEMBLIE A2 S Assembly ID T3 Date Ordered DEPARTMENT Details S ACTIVITY Dept Number MADE AS Dept Data USED IN A3 JOBS Job Number Starting Date USES Ending Date PROCESSES Total Cost Process ID Process Data CUT JOBS PAINT JOBS Cut Job ID FIT JOBS Paint Job IDMachine type Fit Job ID Color used Labor time Volume CUT PROCMaterial used PAINT PROC FIT PROC Labor time Cut Proc ID 28 Laor time Paint Proc ID Fit Proc ID Cuttong Type Paint Method Fit Type Machine Type