DataBase Management Systems (DBMSs) A. Database Concepts 1. Data versus information 2. Key operations a. Define b. Insert c. Delete d. Update e. Data Validation f. Query 3. Database (DB) organization (Relational) DB is a collection of data files File is a collection of records Record is a collection of fields Field is a collection of characters/bytes Characters/Bytes are collections of bits 4. Key field(s) - unique identifier for record 5. Data dictionary - table about the DB itself 6. Query languages a. Query By Example (QBE) b. DB Query Languages (SQL) 7. Advantages of DB a. Eliminate redundancy b. Improved integrity c. Share data d. Reduce Development time e. BACKUP! f. Concurrency control! g. Powerful query languages 8. Other data models a. Hierarchical data a "tree" of information (parents connected to one or more children) b. Network data a "graph" of information (data connected by relationships with other data) c. Object-Oriented data concerns entities and relations with those entities (somewhat like network) often merged with relational (most popular model) B. Information Systems 1. Collections of hardware, software, data, people, procedures 2. Implies management at different levels 3. May include databases, decision systems, etc.