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Chapter 2

Chapter 2. Database Environment. Agenda. Three-Level ANSI-SPARC Architecture Database Languages Data Models Functions of DBMS Components of DBMS Data Dictionary & Information Resource Dictionary System. Three-Level ANSI-SPARC Architecture. External User's view Conceptual

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Chapter 2

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  1. Chapter 2 Database Environment

  2. Agenda • Three-Level ANSI-SPARC Architecture • Database Languages • Data Models • Functions of DBMS • Components of DBMS • Data Dictionary & Information Resource Dictionary System

  3. Three-Level ANSI-SPARC Architecture • External • User's view • Conceptual • Organization view • Constraints, security, & integrity • Internal • Physical presentation • Storage, security, & encryption

  4. Database Schemas • Database schema (intension) & database instance (extension) • External schemas (subschema) • Conceptual schema • Internal schema

  5. Mapping • External/conceptual mapping • Conceptual/internal mapping • Example

  6. Data Independence • Logical data independence • Physical data independence

  7. Database Languages • Data Definition Language (DDL) • Structured Query Language (SQL) • Data Manipulation Language (DML) • Procedural DML • Non-procedural DML • Structured Query Language (SQL) • Query-by-Example (QBE) • Fourth-Generation Language • Form, report, graphics, & application generators

  8. Data Models • Definition • Integrated concept for describing data, relationship and constraints • Types • Object-based data models • Record-based data models • Physical data models (internal structure, ordering, & paths)

  9. Object-Based Data Models • Entity-relationship • Entity, attribute, relationship • Usage • Object-oriented • Object, class, subclass, inheritance, state (attributes), behavior (methods or actions), encapsulation, message, polymorphism • Usage

  10. Record-Based Data Models • Relational data model • Network model • Hierarchical Model

  11. Relational Data Model • Terminology • Relations • Attributes • Tuples • Record relationship • One-to-many relationship • Usage • Ad hoc reporting • Example

  12. Network Model • CODASYL DBTG • Integrated Date Store (IDS) • Terminology • Data item & group item • Record type (owner, member) • Set type: optional, mandatory, permanent • Schema & sub-schema

  13. Network Model • Set • Owner & member • Singular or system • Pointer chains (single-linked, doubly linked, member-to-owner) • Record relationship • Many-to-many relationship • Usage • Large volume transaction processing

  14. Network Model • Schema DDL • Schema description • Area description • Record Description • Set description • Data Manipulation Language (DML) • Host language • Sub-schema DDL

  15. Hierarchical Model • IBM • Information Management Systems • Terminology • Tree, general tree, & subtree • Nodes, root node, child nodes • Segment type • Record relationship • One-to-many relationship • Excellent referential integrity • Inflexible • No many-to-many relationship

  16. Hierarchical Model • Hierarchical record structure (pointer or address) • Level of tree (significant - insignificant) • Pre-order traversal or top down • Post-order traversal or bottom up • Twin pointers, forward links, backward links, logical pointers • Usage • Large volume transaction processing

  17. Functions of a DBMS • Data storage, retrieval and update • A user-accessible catalog • Transaction support • Concurrency control • Recovery • Authorization • Integrity • Data independence • Data communication • Other Utilities

  18. Components of a DBMS • Query processor • Database manager • File manager • DML preprocessor • DDL compiler • Catalog manager

  19. Components of Database Manager • Authorization control • Command processor • Integrity checker • Query optimizer • Transaction manager • Scheduler • Recovery manager • Buffer manager

  20. SYSTEM CATALOGS • Definition • Data dictionary • Information about database • Types • Active • Passive • Integrated • Standalone

  21. Information Resource Dictionary System (IRDS) • IRDS standards by ISO • A set of rules to store and access information in the data dictionary • Objectives: data extensibility, data integrity, & data access control • Service interface works with: panel, command language, export/import files, & application programs

  22. Points to Remember • Three-Level ANSI-SPARC Architecture • Database Languages • Data Models • Functions of DBMS • Components of DBMS • Data Dictionary & Information Resource Dictionary System

  23. Assignment • Review chapter 1-2, appendix c • Read chapter 3 & 4 (skip relational calculus 4.2)

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