Database systems exam 1 questions with correct answers

data vs. information data is raw facts and information is data in context database management is a field that focuses on the proper generation, storage, and retrieval of data Database is a shared integrate computer structure that store a collection of end user data and meta data meta data data about data: the characteristics and relationships that link data i.e. the name of each data element and the type of data stored DBMS database management system basically manages a database and controls access: an intermediary between the user and the database DBMS handles all request and hides the complexity of the database also allow database to be used by many users advantages of DBMS improved data sharing improved data security: framework for managing access minimized data inconsistency improved data access: adhoc queries quick and fast increased decision making increased end user productivity adhoc query a spur of the moment query query result set the answer the database sends back types of databases Single user database: one user at a time Multi-user database: Workgroup database: small number of users types of databases -Centralized database: data located at a single site • Distributed database: data distributed across several different sites several different sites • Operational database: supports a company's day-to-day operations - Transactional or production database Data warehouse : stores data used for tactical or strategic decisions Produce an alphabetic listing on employees by last name SELECT FROM *EMPLOYEE ORDER BY EMPLOYEE_LASTNAME reasons to study file systems • Reasons for studying file systems: - Complexity of database design is easier to understand - Understandingyp p file system problems helps to avoid problems with DBMS systems - Knowledge of file system is useful for converting file system to database system Why is database design important? Designer must identify database's expected use • Well-designed database: designed database: - Facilitates data management - Generates accurate and valuable information • Poorly designed database: - Causes difficult-to-trace errors File systems evolved Initially, computer file systems resembled manual systems • As number of files increased, file systems evolved - Each file used its own application program to store, retrieve, and modify data - Each file was owned by individual or department that commissioned its creation field a character or group of characters which has specific meaning used to define and store data record a logically connected set of fields used to describe a person place or thing file a collection of related records Problems with file systems - lengthy development times: simple data task require a lot of programming - difficult to get quick answers - lack of security and limited data sharing - structurally dependent structurally dependent access to files is dependent of structure of data logical data form vs. physical data form logical: human view vs. physical: the was it actually stored data redundancy same data stored in different places - decreases data security - data incosistency Data anomalies: abnormalities when all changes in redundant data are not made changes in redundant data are not made correctly Good data modeling facilitates communication between the designer, user, and the developer Database system consists of logically related data stored in a single logical data repository - May be physically distributed among multiple storage facilities - DBMS eliminates most of file system's problems - Current generation stores data structures, relationships between structures, and access paths Database system: defines and regulates the collection, storage, management, use of data Five major parts of a database system: - Hardware: all the system's physical devices - Software - People - Procedures - Data Three types of software required - Operating system software - DBMS software DBMS software - Application programs and utility software Who