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File and Database Management Systems Why do we need to take this course ? Why do we need to learn file and/or database management systems? we need to store and retrieve a large collection of data into/from files on disk. We need to do it efficiently and conveniently. Q: What is the file ? What is the file management system? What is the database? What is the database management system? Why should we study file structures ? Why should we study the database management systems? How? Objectives Understand fundamental concepts Textbook Relational database model Query languages and/or SQL File structures: B-tree and hash table Abraham Silberschatz,Henry F.Korth, S.Sudarshan, Database System Concepts (Sixth Edition), Indian Institute of Tecbnology, Bombay,2011 Get hand-on experience Oracle and SQL Development of Java-based database applications JDBC Berkeley DB Course Topics Entity-relationship (ER) model Database design tool Relational database model A set of tables Relational algebra and calculus SQL query language File structures B-tree Hash table Course Administration Grading Re-examination None Collaboration two assignments Two (mini)- projects (group) Midterm Final Collaborate on assignments, but do not merely copy. Moodle Course page forums Evolution of Computer Applications 1. computing machines: Z:= X * Y 2. permanent data storage devices: RAM, disks, tapes 3. file management systems retrieve information efficiently from a large amount of data stored on disk 4. database management systems efficient as well as convenient information retrieval Basic structure of a computer CPU I/O RAM (Random Access Memory) Disk: high capacity with low speed RAM: low capacity with high speed Disk File: a collection of related information defined by its creator. Physical file: a file actually exists in a storage devise. ( a collection of bites, as seen by the operating system.) Logical file: a file viewed by users and programs. ( a collection of records.) A file management system, usually within the operating system, is used to efficiently access physical files stored in the secondary storage devices. Functions: create, updates, retrieval Criterion: efficiency Key consideration: high speed RAM access vs. low speed disk access A file processing system within an operation system a logic file Operating system physical files A file system sets up mappings between logical files and physical files. Data: any information Manufacturing Product data University Student data, courses Hospital Bank Patient data, facilities Account data Database: a large collection of data an integrated collection of data Database management system: a software system that provides an efficient as well as convenient environment for accessing data in a database. Database Management System Structure naive users application programmers casual users database administrator application programs system calls query database scheme data manipulation language precompiler application program object code query processor data definition language compiler database manager DBMS file manager data files data dictionary H.F. Korth and A. Silberschatz. Database System Concepts, McGraw-Hill, 1986. Why file management systems? efficient file accesses Why database management system? efficient and convenient data access File management systems: goal: efficiency problem: high speed ram vs. low speed disk access solution: complicated file structures Database management systems: goal: efficiency as well as convenience problem: conflicts between efficiency and convenience solution: data independence supported by various database models History of File Organizations: Sequential search index sequential B-tree Hashing Get information from a disk file in just a few disk accesses Classification of Database Models: Entity-relationship network Various database models provide hierarchical logical and physical data independence relation to separate simple logical database object-oriented structures and complicated physical deductive file structures.