Lecture 3 note.pptx
- 1. Lecture 3: Organizing Data & Information
- 2. Data Data A necessity for almost any enterprise to carry out its business. Consists of raw facts, and when organized may be transformed into information Database A collection of data organized to meet users’ needs Database management system (DBMS) A group of programs that manipulate the database and provide an interface between the database and the user of the database or other application programs
- 3. Hierarchy of Data Hierarchy of data Example Database Files Records Fields Characters (bytes) Personel file Department file Payroll file (Project database) 005-10-6321 Johns Francine 10-7-65 549-77-1001 Buckley Bill 2-17-79 098-40-1370 Fiske Steven 1-5-85 (Personnel file) 098-40-1370 Feleke Steven 1-5-85 598 (Record containing SSN, last name, first name, date of hire) FELEKE (Last name field) 1000100 (Letter ‘F’ in ASCII)
- 4. Terminology Database A collection of integrated and related files File A collection of related records Record A collection of related fields Field A group of characters Character Basic building block of information, represented by a byte
- 5. Data Entities, Attributes, and Keys Entity A generalized class of people, places, or things (objects) for which data are collected, stored, and maintained E.g., Customer, Employee Attribute A characteristic of an entity; something the entity is identified by E.g., Customer name, Employee name Keys A field or set of fields in a record that is used to identify the record E.g, A field or set of fields that uniquely identifies the record
- 6. Keys and Attributes Key field Attributes (fields) Entities (records) Employee # Last name First name Hire date Dept. # 005-10-6321 Johns Francine 10-7-65 257 549-77-1001 Buckley Bill 2-17-79 650 098-40-1370 Fiske Steven 1-5-85 598
- 7. The Traditional Approach The traditional approach… Separate files are created and stored for each application program Schematic
- 8. Application programs Payroll Payroll programs Reports Data Files Users Invoicing Invoicing programs Reports Inventory control Inventory control programs Reports Management inquiries Management inquiries programs Reports The Traditional Approach
- 9. Drawbacks Data redundancy Duplication of data in separate files Lack of data integrity The degree to which the data in any one file is accurate Program-data dependence A situation in which program and data organized for one application are incompatible with programs and data organized differently for another application
- 10. Database Approach The database approach… A pool of related data is shared by multiple application programs Rather than having separate data files, each application uses a collection of data that is either joined or related in the database Schematic
- 11. Payroll data Inventory data Invoicing Data Other data Database management system Payroll program Inventory program Invoicing program Other programs Reports Reports Reports Reports Database Interface Applications programs Users Database Approach
- 12. Advantages Improved strategic use of corporate data Reduced data redundancy Improved data integrity Easier modification and updating Data and program independence Better access to data and information Standardization of data access A framework for program development Better overall protection of the data Shared data and information resources
- 13. Disadvantages Relatively high cost of purchasing and operating a DBMS in a mainframe operating environment Increased cost of specialized staff Increased vulnerability
- 14. Data Modeling and Database Models (1) Planned data redundancy A way of organizing data in which the logical database design is altered so that certain data entities are combined Summary totals are carried in the data records rather than calculated from elemental data Some data attributes are repeated in more than one data entity to improve database performance
- 15. Data Modeling and Database Models (2) Data model A map or diagram of entities and their relationships Enterprise data modeling Data modeling done at the level of the entire organization Entity-relationship (ER) diagrams A data model that uses basic graphical symbols to show the organization of and relationships between data
- 16. Example: Entity Relationship (ER) Diagram for a Customer Ordering Database Schematic
- 17. Order Customer Product 1:N one-to-many relationship Last name Colour Identification number Name First name Identification number Attributes Entities 1 N
- 18. Hierarchical Database Model Hierarchical database model A data model in which data are organized in a top-down, or inverted tree structure Department C Employee 1 Employee 2 Employee 3 Employee 4 Employee 5 Employee 6 Department B Projects Department A
- 19. Network Data Model Network data model An expansion of the hierarchical database model with an owner-member relationship in which a member may have many owners Project 1 Project 2 Department A Department B Department C
- 20. Relational Data Model Relational data model All data elements are placed in two-dimensional tables, called relations, that are the logical equivalent of files Schematic
- 21. Project Number Description Dept. Number 155 Payroll 257 498 Widgets 632 226 Sales manager 598 Dept. Number Dept. Name Manager SSN 257 Accounting 421-55-99993 632 Manufacturing 765-00-3192 598 Marketing 098-40-1370 SSN Last Name First Name Hire Date Dept. Number 005-10-6321 Johns Francine 10-7-65 257 549-77-1001 Buckley Bill 2-17-79 650 098-40-1370 Fiske Steven 1-5-85 598 Data Table 1: Project Table Data Table 2: Department Table Data Table 3: Manager Table Relational Data Model
- 22. Relational Database Terminology Selecting Data manipulation that eliminates rows according to certain criteria Projecting Data manipulation that eliminates columns in a table Joining Data manipulation that combines two or more tables Linked Relating tables in a relational database together
- 23. Linking Data Tables to Answer an Inquiry Project Number Description Dept. Number 155 Payroll 257 498 Widgets 632 226 Sales manager 598 Dept. Number Dept. Name Manager SSN 257 Accounting 421-55-99993 632 Manufacturing 765-00-3192 598 Marketing 098-40-1370 SSN Last Name First Name Hire Date Dept. Number 005-10-6321 Johns Francine 10-7-65 257 549-77-1001 Buckley Bill 2-17-79 650 098-40-1370 Fiske Steven 1-5-85 598
- 24. Building and Modifying a Relational Database Using Microsoft Access
- 25. Schemas and Subschemas Schema A description of the entire database Subschema A file that contains a description of a subset of the database and identifies which users can perform modifications on the data items in that subset Schematic
- 27. Data Definition Language Data Definition Language (DDL) A collection of instructions and commands used to define and describe data and data relationships in a specific database statements are used to define the database structure or schema. Some examples: CREATE - to create objects in the database ALTER - alters the structure of the database DROP - delete objects from the database TRUNCATE - remove all records from a table, including all spaces allocated for the records are removed COMMENT - add comments to the data dictionary RENAME - rename an object
- 28. Data Manipulation Language (DML) Data Manipulation Language (DML) statements are used for managing data within schema objects. Some examples: SELECT - retrieve data from the a database INSERT - insert data into a table UPDATE - updates existing data within a table DELETE - deletes all records from a table, the space for the records remain MERGE - UPSERT operation (insert or update) CALL - call a PL/SQL LOCK TABLE - control concurrency
- 29. Transaction and data control language Data Control Language (DCL) statements used to control the data modifications. Some examples: GRANT - gives user's access privileges to database REVOKE - withdraw access privileges given with the GRANT command Transaction Control (TCL) statements are used to manage the changes made by DML statements. It allows statements to be grouped together into logical transactions. COMMIT - save work done SAVEPOINT - identify a point in a transaction to which you can later roll back ROLLBACK - restore database to original since the last COMMIT SET TRANSACTION - Change transaction options like isolation level and what rollback segment to use
- 30. Data Dictionary Features Provide a standard definition of terms and data elements Assist programmers in designing and writing programs Simplify database modification Reduce data redundancy Increase data reliability Faster program development Easier modification of data and information
- 31. Logical and Physical Access Paths Logical access path (LAP) Application requires information from the DBMS Physical access path (PAP) DBMS accesses a storage device to retrieve data Schematic
- 32. Data on storage devices DBMS Management inquiries Other software Application programs Physical access path (PAP) Logical access path (LAP)
- 33. Manipulating Data Concurrency control A method of dealing with a situation in which two or more people need to access the same record in a database at the same time Data manipulation language (DML) The commands that are used to manipulate the data in a database Structured query language (SQL) A standardized data manipulation language
- 34. Structured Query Language (SQL) “Invented” at IBM’s Almaden Research Centre (San Jose, CA) in the 1970s E.g., Select all (“*”) columns from the EMPLOYEE table in which the JOB_CLASSIFICATION field is equal to “C2” SELECT * FROM EMPLOYEE WHERE JOB_CLASSIFICATION = “C2”
- 35. Database Output
- 36. Popular Database Management Systems for End Users Microsoft Access Lotus Approach Inprise (formerly Borland) dBASE DBMS Selection Criteria Database size Number of concurrent users Performance Integration Features The vendor Cost
- 37. Distributed Databases Distributed database… A database in which the actual data may be spread across several smaller databases connected via telecommunications devices ‘Pretty’ picture
- 39. Data Warehouse Data warehouse A relational database management system designed specifically to support management decision making Current evolution of Decision Support Systems (DSSs) Data mart A subset of a data warehouse for small and medium-size businesses or departments within larger companies Schematic
- 41. Designing a Customer Data Warehouse Sharply define your goals and objectives before you build the warehouse Choose the software that best fits your goals Determine who/what should be in the database Develop a plan Measure results
- 42. Data Mining Applications Data mining The automated discovery of patterns and relationships in a data warehouse Data mining applications Market segmentation Customer queries Fraud detection Direct marketing Market basket analysis Trend analysis
- 43. On-Line Analytical Processing (OLAP) On-line analytic processing (OLAP) Access to multidimensional databases providing managerially useful display techniques Now used to store and deliver data warehouse information Data warehouse and OLAP Provides top-down, query-driven analysis Data mining Provides bottom-up, discovery-driven analysis
- 44. Open Database Connectivity (ODBC) Open database connectivity (ODBC) A set of standards that ensures software written to comply with these standards can be used with any ODBC-compliant database Schematic
- 45. dBASE ACCESS database Lotus 1-2-3 spreadsheet Paradox database ODBC Import ODBC Link ODBC Export
- 46. Thank You!