Database

Explain DBMS

A Database Management System (DBMS) maximizes the usefulness of a database. DBMSs allow the user to create, modify, and access a database. Common DBMSs include Microsoft Access, Oracle, and Microsoft SQL Server. DBMS software is comprised of five subsystems: ---DBMS engine ---Data definition ---Data manipulation ---Application administration ---Data administration

What's a database?

A database is a collection of related data that can be sorted, logically organized, queried, and stored. Many transactions performed today, including making an online purchase or withdrawing money from an ATM, create data and information that needs to be managed and stored. Databases are used to create a structure for data and allow processed data to be used and interpreted. Databases are a useful tool that turn data into usable information.

Data Integrity

Data integrity means the database is reliable, accurate, and aligned to the goals of the organization. Data centralization is critical in increasing data integrity. Centralized data is stored in only one place. When multiple lists and data sources are maintained, information can become inconsistent leading to decreased data integrity. Essentially, databases enable more efficient data maintenance.

Database Hierarchy

Databases are structured in a hierarchy with characters starting at the lowest point and the database at the highest point. This is diagram represents the hierarchy of data commonly used in databases.

Advantages of using a database

Databases have many advantages when compared to other methods of managing and storing data. Databases allow for the storage of large amounts of data efficiently and securely. Databases enable data sharing and help to ensure data integrity. They also allow for centralization, which is when data is maintained in only one file.

Types of databases

Individual Database ---A combined set of data files intended to be used by one person Company Database ---Created for use by organizations ---Users access the database via computers linked to local or wide area networks. Distributed Database ---The data in a database is stored in different physical locations and accessed via client/server networks. Commercial Database ---Large database that covers specific subjects ---Commercial databases are also referred to as information utilities or data banks.

Lists vs. Databases

Lists work well for simplified tasks, such as items needed to purchase at a grocery store. If the task requires more structure of the data, a database may be more appropriate. If information needs to be organized or made available so multiple people can access it, a list is not a viable solution. Lists can lead to data redundancy, which is the unnecessary duplication of data. Multiple lists of the same data cannot be consistently updated. A lack of proper updating of information can lead to data inconsistency. Data inconsistency occurs when different versions of the same data are present in different portions of the database. Lists are difficult to secure making them more vulnerable to lost or stolen data.

Types of databases - Multidimensional

Multidimensional databases organize and store information in a cube format that can be analyzed using different dimensions. Dimensions allow the data to be analyzed from different perspectives. Data cubes have a measure attribute and a feature attribute. The measure attribute is the main type of data the cube is analyzing. The feature attribute describes the measure attribute in a meaningful way.

Types of databases - Object-oriented

Object-oriented databases store information in objects rather than in tables. Objects contain data and procedures for processing and working with data. Due to this more complex data structure, object-oriented databases allow for more types of data to be stored. Object-oriented databases store instructions for how to compute the data as well as the data to be processed. This allows for faster data processing. Object-oriented databases are equipped to handle unstructured data such as MP4 files, video, images, and extremely large files. Object-oriented databases use Object Query Language to construct queries that extract data from the database.

Types of databases - Relational

Relational databases organize data into tables based on structured data groupings. Relational databases use links, called relationships, between tables. Information in tables is stored in rows called records, and columns called fields. These relationships define how the data in the tables is related. A common field that is included in both tables is used to create the relationship.

DBMS Subsystems - The Engine

The DBMS engine provides an interface between the logical view (front-end) and physical view (back-end) of the data. For example, if a user requests data, such as a username or password, this is done through the logical view. The DBMS handles the request and finds the information in the physical view, or back-end of the program. End users interface with the logical view of a database, while programmers and administrators interface with the physical view of the database.

DBMS Subsystems - Application Generation

The application generation subsystem includes tools that create forms and reports and programming languages such as Visual Basic and Java. Application generation subsystems include tools for creating visually appealing data entry screens and for creating easy to use data entry screens.

DBMS Subsystems - Data Administration

The data administration subsystem allows for the management of the database. Management features include data recovery, support, maintaining the operations of the database, and security. In both large and small organizations these tasks are often handled by a database administrator (DBA). DBAs are tasked with maintaining the database, assigning access rights, and interacting with and/or designing the database.

DBMS Subsystems - Data Definition

The data definition subsystem describes the logical construction of the database using a data dictionary or data schema. The data dictionary of a database contains descriptions of the data structure. Each unit of data in a database is defined using a variety of criteria including field names and the type of data each field contains: ---Text ---Date/time ---Numeric ---Graphic ---Audio ---Video

DBMS Subsystems - Data Manipulation

The data manipulation subsystem allows for data maintenance and data analysis. The data manipulation subsystem includes a data maintenance feature which permits adding, deleting, and editing data in the database. A variety of tools, including queries and reports, are part of the data manipulation subsystem. Most database subsystems use a specific programming language called structured query language (SQL).