!" #Chris Irwin Davis, Ph.D.Email: [email protected]: (972) 883-3574Office: ECSS 4.705Chapter 1: Databases and Database UsersCS-6360 Database Systems!" #Outline• 1.1 –!Introduction• 1.2 –!An Example• 1.3 –!Characteristics of the Database Approach• 1.4 –!Actors on the Scene• 1.5 –!Workers behind the Scene• 1.6 –!Advantages of Using the DBMS Approach • 1.7 –!A Brief History of Database Applications• 1.8 –!When Not to Use a DBMS21.1 Introduction!" #What is a Database?• Database °Collection of related data°Known facts that can be recorded and that have implicit meaning°Miniworld or Universe of Discourse (UoD)°Represents some aspect of the real world°Logically coherent collection of data with inherent meaning (semantics)°Built for a specific purpose4!" #Examples• Traditional database applications°Store textual and/or numeric information, such as the Medicare database.• Multimedia databases°Store images, audio clips, and video streams digitally. Most modern DBMSs can do this• Geographic information systems (GIS) °Store and analyze maps, weather data, and satellite images5!" #Examples• eCommerce°eBay, Amazon, etc.• Data warehouses and online analytical processing (OLAP) systems °Extract and analyze useful business information from very large databases °Support decision making• Real-time and active database technology °Control industrial and manufacturing processes6!" #Database Management System (DBMS)• A suite of programs that allows a user to create and maintain a database.• You can specify the types of data, relationships between various data elements, and constraints on what can be stored.• Metadata describes the data, and is stored in the database. Also called a data dictionary.• A schema is the structure of the database7!" #Database Management System (cont’d)• DBMSs allow you to manipulate the database, both the schema and the actual data.• You can query the database to retrieve information based upon criteria.• You can update the database, which includes adding new information, changing existing information, and removing records.• DBMSs are generally multi-user; they support requests from large numbers of users8!" #Database Management System (cont’d)• DBMSs generally provide security, both in terms of encrypting sensitive data and limiting access to authorized users.• DBMSs provide a programming interface (API) to allow you to write programs to interact with the database.9!" #Practical Stuff• There are two readily-available DBMSs: • Microsoft SQL Server°The professional version is free to you as a UTD student, while the express edition is free to everyone.• MySQL from Oracle°There is a free version of this, and that’s what I’ll be using for most of my examples• You can download Java libraries for either one. I suggest you do this soon.10!" #Implementation Terminology• Table – A set of data records of the same format, divided into columns that all contain the same kind of data, and rows of related records.• View – A composite of various related tables• Stored Procedure – A set of SQL statements that can be parameterized and executed.11!" #Terminology12Relational AlgebraDatabaseRelationTableFieldColumnTupleRow!" #Data Types• Each column (field, data element) is of a specific type. Data types can include:°Fixed-length strings°Variable-length strings°Dates°Integers°Floating-point numbers°BLOBs (binary large objects).131.2 An Example!" #An Example•UNIVERSITY database °Information concerning students, courses, and grades in a university environment•Data records (tables)°STUDENT °COURSE°SECTION °GRADE_REPORT °PREREQUISITE15!" #An Example (cont’d)• Construct UNIVERSITY database°Store data to represent each student, course, section, grade report, and prerequisite as a record in appropriate file• Relationships among the records• Manipulation involves querying and updating16!" #An Example (cont’d)• A good question to ask when designing a database is “What will you want to know from it?” • For example:°Retrieve the transcript°List the names of students who took the section of the ‘Database’ course offered in fall 2013 and their grades in that section°List the prerequisites of the ‘Database’ course17!" #An Example (cont’d)• Examples of updates:°Change the class of ‘Smith’ to sophomore°Create a new section for the ‘Database’ course for this semester°Enter a grade of ‘A’ for ‘Smith’ in the ‘Database’ section of last semester18!" #University Database19!" #Phases for Designing a Database• Requirements specification and analysis °Does this sound like software engineering?• Conceptual design°ER Model (Chapter 7)• Logical design°Relational Model (Chapter 3)• Physical design201.3 Characteristics of the Database Approach!" #The Traditional File Approach•In traditional file processing… °Each user defines and implements the files needed for a specific software application-This is not strictly true; usually we designed suites of applications that used common files. -However, the layout of the files was defined in the code, not in the file. (e.g. preferences files, configuration files)22!" #The Database Approach•Single repository maintains data that is defined once and then accessed by various users, and the database contains the layout.•Self-describing nature of a database system•Insulation between programs and data, and data abstraction•Support of multiple views of the data•Sharing of data and multiuser transaction processing23!" #Self-Describing Database•Database system contains complete definition of structure and constraints•Meta-data°“Database Catalog” – Describes structure of the database•Database catalog used by: °DBMS software °Database users who need information about database structure24!" #Database Catalog (i.e. Meta-data) Example25!" #Insulation Between Programs and Data• Program-data independence°Structure of data files is stored in DBMS catalog separately from access programs• Program-operation independence"°Operations specified in two parts:- Interface includes operation name and data types of its arguments - Implementation can be changed without affecting the interface26!" #Support of Multiple Views of the Data• View °Subset of the database °Contains virtual data derived from the database files but is not explicitly stored• Multiuser DBMS
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