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Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe  CHAPTER 1 Databases and Database Users Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0  OUTLINE Types of Databases and Database Applications Basic Definitions Typic...

Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe  CHAPTER 1 Databases and Database Users Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0  OUTLINE Types of Databases and Database Applications Basic Definitions Typical DBMS Functionality Example of a Database Main Characteristics of the Database Approach Types of Database Users Advantages of Using the Database Approach Extending Database Capabilities When Not to Use Databases Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0  Types of Databases and Database Applications Traditional Applications: Numeric and Textual Databases More Recent Applications: Multimedia Databases Geographic Information Systems (GIS) Biological and Genome Databases Data Warehouses Mobile databases Real-time and Active Databases First part of book focuses on traditional applications A number of recent applications are described later in the book (for example, Chapters 24,25,26,27,28,29) Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0  Recent Developments (1) Social Networks started capturing a lot of information about people and about communications among people-posts, tweets, photos, videos in systems such as: - Facebook - Twitter - Linked-In All of the above constitutes data Search Engines, Google, Bing, Yahoo: collect their own repository of web pages for searching purposes Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0  Recent Developments (2) New technologies are emerging from the so- called non-SQL, non-database software vendors to manage vast amounts of data generated on the web: Big data storage systems involving large clusters of distributed computers (Chapter 25) NOSQL (Non-SQL, Not Only SQL) systems (Chapter 24) A large amount of data now resides on the “cloud” which means it is in huge data centers using thousands of machines. Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0  Basic Definitions Database: A collection of related data. Data: Known facts that can be recorded and have an implicit meaning. Mini-world: Some part of the real world about which data is stored in a database. For example, student grades and transcripts at a university. Database Management System (DBMS): A software package/system to facilitate the creation and maintenance of a computerized database. Database system: The DBMS software together with the data itself. Sometimes, the applications are also included. Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0 Data & Related Disciplines Human-Computer Interaction Data Visualization Databases Information Retrieval Machine Learning Data Access Data Analysis Data Mining Computer Vision Speech Recognition Data Understanding Data Integration Natural Language Processing Data Warehousing Formatting, Cleaning Signal Processing Many Applications! Storage Data Information Theory Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe  Impact of Databases and Database Technology Businesses: Banking, Insurance, Retail, Transportation, Healthcare, Manufacturing Service industries: Financial, Real-estate, Legal, Electronic Commerce, Small businesses Education : Resources for content and Delivery More recently: Social Networks, Environmental and Scientific Applications, Medicine and Genetics Personalized applications: based on smart mobile devices Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0 Simplified database system environment Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0  Typical DBMS Functionality Define a particular database in terms of its data types, structures, and constraints Construct or load the initial database contents on a secondary storage medium Manipulating the database: Retrieval: Querying, generating reports Modification: Insertions, deletions and updates to its content Accessing the database through Web applications Processing and sharing by a set of concurrent users and application programs – yet, keeping all data valid and consistent Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0  Application Activities Against a Database Applications interact with a database by generating - Queries: that access different parts of data and formulate the result of a request - Transactions: that may read some data and “update” certain values or generate new data and store that in the database Applications must not allow unauthorized users to access data Applications must keep up with changing user requirements against the database Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0  Additional DBMS Functionality DBMS may additionally provide: Protection or Security measures to prevent unauthorized access “Active” processing to take internal actions on data Presentation and Visualization of data Maintenance of the database and associated programs over the lifetime of the database application Called database, software, and system maintenance Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0 Example of a Database Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0 Example of a Database (cont..) Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0 Example of a Database (cont..) Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0 Example of a Database (cont..) Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0  Another Example of a Database (with a Conceptual Data Model) Mini-world for the example: Part of a UNIVERSITY environment Some mini-world entities: STUDENTs COURSEs SECTIONs (of COURSEs) (Academic) DEPARTMENTs INSTRUCTORs Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0  Example of a Database (with a Conceptual Data Model) Some mini-world relationships: SECTIONs are of specific COURSEs STUDENTs take SECTIONs COURSEs have prerequisite COURSEs INSTRUCTORs teach SECTIONs COURSEs are offered by DEPARTMENTs STUDENTs major in DEPARTMENTs Note: The above entities and relationships are typically expressed in a conceptual data model, such as the entity- relationship (ER) data or UML class model (see Chapters 3, 4) Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0 Example of a Simple Database Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0  Main Characteristics of the Database Approach Self-describing nature of a database system: A DBMS catalog stores the description of a particular database (e.g. data structures, types, and constraints) The description is called meta-data*. This allows the DBMS software to work with different database applications. Insulation between programs and data: Called program-data independence. Allows changing data structures and storage organization without having to change the DBMS access programs. * Some newer systems such as a few NOSQL systems need no meta-data: they store the data definition within its structure making it self describing Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0 Example of a Simplified Database Catalog Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0  Main Characteristics of the Database Approach (continued) Data abstraction: A data model is used to hide storage details and present the users with a conceptual view of the database. Programs refer to the data model constructs rather than data storage details Support of multiple views of the data: Each user may see a different view of the database, which describes only the data of interest to that user. Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0  Main Characteristics of the Database Approach (continued) Sharing of data and multi-user transaction processing: Allowing a set of concurrent users to retrieve from and to update the database. Concurrency control within the DBMS guarantees that each transaction is correctly executed or aborted Recovery subsystem ensures each completed transaction has its effect permanently recorded in the database OLTP (Online Transaction Processing) is a major part of database applications; allows hundreds of concurrent transactions to execute per second. Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0  Database Users Users may be divided into Those who actually use and control the database content, and those who design, develop and maintain database applications (called “Actors on the Scene”), and Those who design and develop the DBMS software and related tools, and the computer systems operators (called “Workers Behind the Scene”). Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0  Database Users – Actors on the Scene Actors on the scene Database administrators Responsible for authorizing access to the database, for coordinating and monitoring its use, acquiring software and hardware resources, controlling its use and monitoring efficiency of operations. Database designers Responsible to define the content, the structure, the constraints, and functions or transactions against the database. They must communicate with the end-users and understand their needs. Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0  Database End Users Actors on the scene (continued) End-users: They use the data for queries, reports and some of them update the database content. End-users can be categorized into: Casual: access database occasionally when needed Naïve or parametric: they make up a large section of the end-user population. They use previously well-defined functions in the form of “canned transactions” against the database. Users of mobile apps mostly fall in this category Bank-tellers or reservation clerks are parametric users who do this activity for an entire shift of operations. Social media users post and read information from websites Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0  Advantages of Using the Database Approach Controlling redundancy in data storage and in development and maintenance efforts. Sharing of data among multiple users. Restricting unauthorized access to data. Only the DBA staff uses privileged commands and facilities. Providing persistent storage for program Objects E.g., Object-oriented DBMSs make program objects persistent– see Chapter 12. Providing storage structures (e.g. indexes) for efficient query processing – see Chapter 17. Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0  Advantages of Using the Database Approach (continued) Providing optimization of queries for efficient processing Providing backup and recovery services Providing multiple interfaces to different classes of users Representing complex relationships among data Enforcing integrity constraints on the database Drawing inferences and actions from the stored data using deductive and active rules and triggers Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0  When not to use a DBMS Main inhibitors (costs) of using a DBMS: High initial investment and possible need for additional hardware Overhead for providing generality, security, concurrency control, recovery, and integrity functions When a DBMS may be unnecessary: If the database and applications are simple, well defined, and not expected to change If access to data by multiple users is not required When a DBMS may be infeasible In embedded systems where a general-purpose DBMS may not fit in available storage Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0  When not to use a DBMS When no DBMS may suffice: If there are stringent real-time requirements that may not be met because of DBMS overhead (e.g., telephone switching systems) If the database system is not able to handle the complexity of data because of modeling limitations (e.g., in complex genome and protein databases) If the database users need special operations not supported by the DBMS (e.g., GIS and location- based services). Copyright © 2016 Ramez Elmasri and Shamkant B. Navathe Slide 1- 0