Chapter 1 Database Systems

The main functions of a database management system (DBMS)

-The DBMS serves as the intermediary between the user and the database. -The DBMS receives all application requests and translates them into the complex operations required to fulfill those requests. DBMS functions: - Data dictionary management: The DBMS stores definitions of the data elements and their relationships (metadata),in a data dictionary. The DBMS uses the data dictionary to look up the required component structures and relationships, thus relieving you from having to code such complex relationships in each program. - Data storage management- The DBMS creates and manages the complex structures required for data storage, thus relieving you from the difficult tasks of defining and programming the physical data characteristics. Data storage management is also important for performance tuning, which relates to the activities that makes the database perform more efficiently in terms of storage and access speed. -Data transformation and presentation- The DBMS transforms entered data to conform to required data structures. -Security Management- The DBMS creates a security system that enforces user security and data privacy. - Multiuser Access Control- To provide data integrity and data consistency, the DBMS uses sophisticated algorithms to ensure that multiple users can access the database concurrently without compromising its integrity. - Backup and Recovery management- The DBMS provides backup and data recovery to ensure data safety and integrity. - Data integrity management-The DBMS promotes and enforces integrity rules, thus minimising data redundancy and maximising data consistency. - Database access languages and application programming interfaces- The DBMS provides data access through a query language. A query language is nonprocedural languages- one that lets the user specify what must be done without having to specify how. Structured Query Language (SQL) is the de facto query language and data access standard support by the majority of DBMS vendors. The advantages of a DBMS are: - Improved data sharing -Improved data security -Better data integration -Minimized data inconsistency -Improved data access -Improved decision making - Increased end-user productivity The disadvantages of a DBMS are: -Increased costs -Management complexity -Maintaining currency (staying current) - Vendor dependency -Frequent upgrade/replacement cycles

What a database is, the various types of databases, and why they are valuable assets for decision making.

A database is a shared, integrated computer structure that stores: 1) End-user data- raw facts of interest to the end user. 2) Metadata- data about data- through which the end-user data are integrated and managed The types of databases are: - Single-user database (supports one user) on a personal computers is called a desktop database - Multiuser database (supports multiple users). Less than 50 or for a specific department in a business is called a workgroup database. More than 50 and across many departments is an enterprise database. - Centralised database (supports data located at a single site) - Distributed database (supports data across several different sites) - Cloud database (is created and maintained using cloud data services such as Microsoft Azure) - General-purpose databases (contain a wide variety of data used in multiple disciplines) - Discipline-specific databases (contain data focused on specific subject areas) - Operational database/online transaction processing (OLTP)/transactional/production database (supports a company's day to day operations) - Analytical database (stores historical data and business metrics used exclusively for tactical or strategic decision making. An analytical database is made of a data warehouse and an online analytical processing (OLAP) front end. The data warehouse is a specialised database that stores data in a format optimised for decision support. Online analytical processing (OLAP) is a set of tools that work together to provide an advanced data analysis environment for retrieving, processing, and modelling data from the data warehouse.

Query

A query is a specific request issued to the DBMS for data manipulation.

The difference between data and information

Data are raw facts while information is the result of processing raw data to reveal its meaning. To reveal meaning, information requires context. Knowledge is the body of information and facts about a specific subject.

Data inconsistency

Data inconsistency is when different versions of the same data appear in different places.

Data management

Data management is a discipline that focuses on the proper generation, storage, and retrieval of data.

Data quality

Data quality is a comprehensive approach to promoting the accuracy, validity, and timeliness of the data.

Unstructured Data

Data that exists in their original(raw) state- that is, in the format in which they are collected.

Semistructured Data

Data that has been processed to some extent.

The importance of database design.

Database design refers to the activities that focus on the design of the database structure that will be used to store and manage end-user data.

Business Intelligence

Describes a comprehensive approach to capture and process business data with the purpose of generating information to support business decision making.

Extensible Markup Language (XML)

Extensible Markup Language (XML) is a special language used to represent and manipulate data elements in a textual format.

A database management system (DBMS)

Is a collection of programs that manages the database structure and controls access to the data stored in the database.

Ad hoc query

Is a spur-of-the-moment question. The DBMS sends back an answer called the query result set.

About flaws in file system data management

Lengthy development times-The first and most glaring problem with the file system approach is that even the simplest data-retrieval task requires extensive programming. Difficulty of getting quick answers-The need to write programs to produce even the simplest reports makes ad hoc queries impossible. Complex system administration- System administration becomes more difficult as the number of files in the system expands. Lack of security and limited data sharing-Another fault of a file system data repository is a lack of security and limited data sharing. Extensive programming- Making changes to an existing file structure can be difficult in a file system environment. A file system exhibits structural dependence- Structural dependent means that access to a file is dependent on its structure. Structural independence exists when you can change the file structure without affecting the application's ability to access the data. Data Redundancy- Data redundancy is when the same data is stored unnecessarily at different places. Uncontrolled data redundancy can lead to: Poor data security- Having multiple copies of data increases the chances for a copy of the data to be susceptible to unauthorised access. Data inconsistency- Data inconsistency exists when different and conflicting versions of the same data appear in different places. Data-entry errors are more likely to occur when complex entries are made in several different files or recur frequently in one or more files. Data anomalies- Develops when not all of the required changes in the redundant data are made successfully. (Update, Insertion and Deletion)

How modern databases evolved from file systems.

N/A

XML database

Supports the storage and management of semiunstructured XML data

The main components of the database system

The database system refers to an organisation of components that define and regulate the collection, storage, management, and use of data within a database environment. The five components are: -Hardware -Software (Operating System software, DBMS software & Application programs and utility software) -People (System Administrators oversee the database's system's general operations, Database administrators manage the DBMS and ensure the database is functioning properly, Database designers design the database structure, System analysts and programmers design and implement the application programs and end users are the people who use the application programs to run the organisation's daily operations) -Procedures - are the instructions and rules that govern the design and use of the database system. -Data- The word data covers the collection of facts stored in the database.

Structured Data

The result of formatting unstructured data to facilitate storage, use, and the generation of information.

NoSQL

is generally used to describe a new generation of database management systems that is not based on the traditional relational database model.

Social media

refers to web and mobile technologies