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58 Cards in this Set
- Front
- Back
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What is a Database?
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A shared, integrated computer structure that stores a collection of: end-user data (raw facts of use to end-user); meta-data (data about data)
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What is Data Management?
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A discipline that focuses on the proper generation, storage and retrieval of data; core activity of any business, Govt. agency, service organisation or charity.
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What is Knowledge?
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The body of information & facts about a specific subject; implies familiarity, awareness and understanding of information as is applies to an environment; "new" knowledge can be derived from "old" knowledge.
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What is Information?
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The result of processing raw data to reveal its meaning; used to reveal the meaning of data; accurate, relevant and timely information is the key to good decision making; bedrock of knowledge.
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What is Data?
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Raw facts; not yet processed to reveal its meaning; building blocks of information.
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What is a Database Management System (DBMS)?
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A collection of programs to manage database structure and control access to data; helps manage contents; intermediary between user and database; hides internal complexity and presents integrated view of data; translates requests into complex operations required.
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What are the advantages of a DBMS?
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Enables data to be shared among multiple applications or users; integrates many different user's views into a single all encompassing data repository; improves data sharing; better data integration, improved data access; increased end-user productivity; improved data security; minimised data inconsistency; improved decision-making.
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What is Data Inconsistency?
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Exists when different versions of the same data appear in different places; a condition in which different versions of the same data yield different (inconsistent) results.
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What is Meta-data?
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Data about data; through which the end-user data are integrated and managed; provide a description of data characteristics and the set of relationships that link the data in the database; may include name, type, is_null of each element.
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What is a Query?
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A specific request issued to the DBMS for data manipulation, eg. to read or update the data; simply put - a query is a question, an ad hoc query is spur of the moment.
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What are some different types of databases?
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single user database; desktop database; multi-user database; work-group database; enterprise database; centralised database; -distributed database; - production/operational/transactional database; data warehouse
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What is a single-user database?
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A single-user database only supports on user at a time.
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What is a multi-user database?
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A multi-user database supports multiple users at the same time.
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What is a desktop database?
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A desktop database is a single user database that runs on a personal computer.
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What is a work-group database?
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A work-group database is a multi-user database that supports usually 50 or less users or a specific department in an organisation.
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What is an enterprise database?
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An enterprise database is used by an entire organisation across many departments (>50 users).
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What is a centralised database?
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A centralised database supports data located at a single site.
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What is a distributed database?
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A distributed database supports data distributed across different sites.
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What is an operational/transactional/production database?
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An operational database supports an organisations day-to-day operations.
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What is a Data Warehouse?
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A data warehouse focuses primarily on storing data used to generate information for strategic or tactical decisions; - historical, not updated
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How can databases be classified?
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Databases can be classified by: number of users; database locations, expected type & extent of use; the degree to which the data are structured.
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What are unstructured data?
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Data that exist in original (raw) state; in the format in which collected; in format that does not lend itself to the processing that yields information.
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What are structured data?
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The results of taking unstructured data and formatting (structuring) to facilitate storage, use and generation of information; - semi-structured data are data already processed to some extent.
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What is XML?
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Extensible Markup Language is a special language used to represent and manipulate data elements in textual format.
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What is an XML database?
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An XML database supports the storage and management of semi-structured XML data.
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What is Database Design?
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-refers to activities that focus on the design of the database structurethat will be used to store and manage end-user data; -identifies precisely the expected use and is necessary to meet all user requirements
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What are the design considerations of a transactional database?
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-emphasises accurate and consistent data; -operational speed.
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What are the design considerations of a data warehouse database?
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recognises the use of historical and aggregated data.
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Why is database design important?
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- a well designed database facilitates data management and generated accurate and valuable information; -poorly designed databases breed difficult-to-trace errors that may lead to bad decision making
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Why study the use of file systems in managing data?
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Understanding of relatively simple characteristics of the file system makes the complexity of database design easier to understand; - awareness of problems that plagued file systems to help avoid pitfalls with DBMS software; - in converting obselete file system to a database system, knowledge of file system's basic limitations will be useful.
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In file system terminology, what is data?
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Data is raw data, little meaning unless organised in a logical manner; - smallest recognised piece is a single character -> requires 1 byte of computer storage
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In file system terminology, what is a field?
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A field is character(s) that have specific meaning and are used to define a characteristic of a person, place, or thing and store data.
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In file system terminology, what is a record?
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A record is a logically connected set of fields that describe a person, place or thing.
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In file system terminology, what is a file?
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A file is a collection of related records.
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What is a Data Processing (DP) specialist
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A DP specialist is responsible for the conversion of manual file systems to a matching computer file system: - created necessary computer file structures and often wrote the software that managed the data within these structures; - designed application programs that produced reports based on the file data.
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How did the DP specialist's job evolve?
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Due to increase in organisation's number of files and the complexity of the file system, this required additional programming and computer resources;- DP specialists evolved to DP manager to supervise DP departments managing technical and human resources of additional programming staff.
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What are the problems with file system data management?
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- required extensive programming; - cannot perform ad hoc queries; - system administration can be complex and difficult; - difficult to make changes to existing structures; - security features likely to be inadequate; these issues lead to problems of structural and data dependency.
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What is Structural Dependence?
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- access to a file is dependent on its structure; - it is not possible to make changes in the file structure without affecting the application program's ability to access the data.
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What is Data Dependence?
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When data access programs are subject to change when any of the file's data storage characteristics change (i.e.. changing the data type); - whien is is not possible to make changes to the data storage characteristics without affecting the application program's ability to access the data.
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What is the Logical Data Format?
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The logical data format is how the human being or end-user views the data.
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What is the Physical Data Format?
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The physical data format is how the computer "sees" and must work with the data.
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What is Data Redundancy?
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Date redundancy exists when the same data are stored unnecessarily at different places; - organisation structure (file data systems) promote storage of same basic data at different locations (islands of information); -sets the stage for - data inconsistency ; - data anomalies.
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What is Data Inconsistency?
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Data Inconsistency exists when different and conflicting versions of the same data appear in different places; - also lacks data integrity;
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What is Data Integrity?
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Data integrity means that : - data are accurate, no data inconsistencies; - data are verifiable; always yields consistent results.
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What is a Data Anomaly?
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- data redundancy fosters "abnormal" conditions by forcing field value changes in many different locations. :- a data anomaly occurs when all of the required changes in the redundant data are not made successfully. They include : update, insertion and deletion anomalies.
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What is the Database System?
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The organisation of components that define and regulate the collection, storage, management and use of data within a database environment: 5 major parts: - hardware, software, people, procedures/policies, data
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What are the main DBMS functions?
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- data dictionary management; - data storage management; - data transformation and presentation; - security management; -multi-user access control; - backup and recovery management; - data integrity management; - database access language and application programming interfaces; - database communication interfaces.
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Discuss Data Dictionary Management.
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The DBMS stores definitions of data elements and their relationships (meta-data) in a data dictionary. Programs access data through the DBMS. The DBMS used the data dictionary to look up required data component structures and relationships relieving the need to code complex relationships in each program. Changes made to database structure are automatically recorded in the data dictionary. Provides data abstraction, removes structural and data dependency.
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Discuss Data Storage Management.
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The DBMS creates and manages complex structures required for data storage, relieving you from difficult task of defining and programming physical data characteristics. Also stores related data entry forms or screen definitions, report definitions, data validity rules and procedural code etc. Data storage management is also important for database performance tuning: - relates to activities that make databases perform more efficiently in terms of storage and access speed.
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Discuss Data Transformation and Presentation.
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The DBMS transforms entered data to conform to required data structures which relieves you of making distinctions between logical and physical data formats. Also formats physically retrieved data to make it conform to users logical expectations. Eg UK and US date formats.
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Discuss Security Management.
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The DBMS creates a security system that enforces user security and data privacy. Security rules determine which users can access the database, which data items the user can access and which data operations the user can perform. :- important in multi-user database systems; -authentications of users through user name/password or biometrics; - DBMS uses this info to assign access privileges to database components e.g. queries/reports.
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What is Multi-user Access Control?
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To provide data integrity and data consistency, the DBMS uses sophisticated algorithms to ensure multiple users can access the database concurrently without compromising the integrity of the database.
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What is Backup and Recovery Management?
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The DBMS provides backup and recovery to ensure data safety and integrity. Current DBMS systems provide special utilities to allow the DBA to perform routine and special backup/restore procedures. Recovery management deals with the recovery of the database after a failure such as a bad sector on a disk or a power failure. This is critical to preserving database integrity.
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What is Data Integrity Management?
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The DBMS promotes and enforces integrity rules, thus minimising redundancy and maximising data consistency. The data relationships stored in the data dictionary are used to enforce data integrity. This is especially important in transaction-oriented database systems.
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What are Data Access Languages?
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The DBMS provides data access through a query language. This is a non-procedural language - one that lets users specify what is to be done without specifying how it is to be done. SQL- (Structured Query Language) is the de facto query language and data access standard supported by most DBMS vendors.
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What are Application Programming Interfaces?
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The DBMS also provides APIs to procedural languages (COBOL, C, Java, VB.NET, C++). It also provides administrative utilities used by the DBA/database designers to create, implement, monitor and maintain the database.
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What are Database Communication Interfaces?
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Current generations DBMSs accept end-user requests via multiple network environments, Eg, the DBMS might provide access to the database via the Internet through the use of web browsers eg Firefox/IE. In this environment, communication can be achieved in several ways.: - end-user generated answers to queries by filling in screen forms in favourite browsers: - DBMSs automatically publishes predefined reports on a website:- DBMS can connect to 3rd party systems to distribute information via email or other productivity applications.
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What are the disadvantages of Database Systems?
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Increased cost; sophisticated software/hardware/skilled personnel, training, licensing, regulations compliance costs; management complexity; maintaining currency; frequent updates, latest patches, security measures, updated training; vendor independence; reluctance to change vendors due to investments in technology and training: frequent upgrade/replacement cycles: new features may demand new equipment and additional training.
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