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Database management Systems �A database administration system (DBMS), or database program, is software that permits you come create, access, and manage a database. �DBMSs are accessible for numerous sizes and varieties of computers.




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Database monitoring Systems


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Data dictionary �A data dictionary, sometimes called a repository, has data about each ar in those files. �For each file it shop details such as the paper name, description, the file’s connection to various other files, and also the variety of records in the file. �For each field, it stores the ar name, description, ar type, field size, default value, validation rules, and also the field’s relationship to other fields.


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Data thesaurus �Because the data dictionary contains details around data, some call it metadata, meta meaning more comprehensive. �It is a an essential backbone come a DBMS so only skilled professionals must update the contents. �It is offered to execute validation checks and also limit the type of data that deserve to be entered.


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Data dictionary �A data dictionary allows users to specify a default worth for a field, i beg your pardon is a worth that the DBMS initially display screens in a field. ◦ Ex. If most students live in Indiana, the default value might read ‘IN’. �The user doesn’t have actually to kind the default value which help in to reduce errors.


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Data dictionary


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File Retrieval and also Maintenance �A DBMS offers several devices that enable users and programs to retrieve and maintain data in the database (adding, modifying, and also deleting). �To retrieve or choose data in a database, you query it, which is a inquiry for certain data from the database. �Users have the right to instruct the DBMS come display, print, or save the outcomes of a query, make it among the more powerful database features.


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Query Language �A ask language is composed of simple, English-like explanation that allow users come specify the data to display, print, or store. �Each has actually its own grammar and vocabulary. �A person without programming experience have the right to learn a query language in a brief time. �Most queries are supplied to retrieve data. �Some DBMSs carry out wizards to guide


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Query by instance �Most DBMSs encompass query by instance (QBE), a function that has a graphical user interface to aid users through retrieving data.


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Form �A form, sometimes dubbed a data entrance form, is a window on the screen that provides locations for start or modifying data in a database. �Well-designed creates should validate data as it is entered. �A type that sends gone into data throughout a network or the web is dubbed an eform, short for electronic form. �E-forms typically use a means to certain the data while that is transported throughout the network.


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Form


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Report Generator �A report generator, additionally called a report writer, enables users to style a report top top the screen, retrieve data into the report design, and then display or publish the report. �Unlike a form, report generators have the right to only retrieve data. �Report generators permit you to style the page and some allow you to create a report as a net page.


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Report Generator


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Data defense �A DBMS provides way to for sure that just authorized users can accessibility data at permitted times. �Most DBMSs permit different levels of accessibility privileges to be determined for each field in the database, defining the actions that a details user or group can perform.


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Data protection �Access privileges because that data involve establishing who deserve to enter new data, change existing data, delete undesirable data, and view data. ◦ Ex. A student would have read-only privileges: enabling them to see the list of readily available classes yet not change them. ◦ Ex. A room head would have the ability to modify the data. ◦ Ex. Other users would have actually no access privileges to the data.


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Data protection �Many organizations embrace a rule of the very least privilege policy, wherein users’ access privileges are minimal to the shortest level essential to perform forced tasks.


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Backup and also Recovery �Occasionally a database is damaged or destroyed, for this reason a DBMS offers a selection of techniques to gain back the database come a usable form. �A backup, or copy, the the entire database should be make on a regular basis. �Some DBMSs have a built-in back-up utility if others require a separate utility.


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Backup and Recovery �More facility DBMSs preserve a log, which is a listing of tasks that modify the contents of the database. ◦ Ex. A it is registered clerk modifies a student’s address, the readjust will appear in the log. �The log in contains: ◦ A copy the the record before the readjust called the prior to image ◦ The readjust being made ◦ and a copy of the document after the adjust called the after picture ◦ The log in may likewise store who made the change and when.


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Backup and also Recovery �DBMSs that develop logs usually administer a restore unit, which offers the logs and/or backups to regain a database as soon as it becomes damaged or damaged using rollforward and also rollback techniques. �In a rollforward, or front recovery, the DBMS provides the log in to reenter transforms made to the database because the last save or backup. �In a rollback, or backward recovery, the DBMS provides the log in to undo any type of changes made come the database during a details


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Backup and also Recovery �Continuous backup is a backup plan in which all data is backed up whenever a change is made. �Continuous back-up provides recovery in a matter of seconds. �This method can cost more but is growing in popularity because of its benefits.


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Relational, Object-Oriented, and Multidimensional Databases �Every database and also DBMS is based on a details data model. �A data model consists of rules and also standards that define how the database organizes data.


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Relational, Object-Oriented, and also Multidimensional Databases �Three renowned data models in use today space relational, object-oriented, and multidimensional. �Some are called object-relational databases due to the fact that they combine features that the relational and objectoriented data models.


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Relational Databases �A relational database is a database the stores data in tables that consist that rows and also columns. �Each row has actually a primary crucial and each column has actually a distinct name. �A developer the a relational database describes a document as a relation, a document as a tuple, and also a ar as one attribute.


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Relational Databases �A user of a relational database describes a record as a table, a record as a row, and a ar as a column. �In addition to save data, a relational database likewise stores data relationships, i m sorry are links within the data. �With a relational database, girlfriend can set up a relationship between tables with common fields.


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Relational Databases


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Relational Databases �A developer the relational databases supplies normalization to organize the data in the database. �Normalization is a process designed to ensure the data in ~ the relations (tables) consists of the least amount that duplication.


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SQL �Structured ask Language (SQL) is a popular query language that enables users come manage, update, and also retrieve data. �SQL has special keywords and also rules the users include in SQL statements.


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Object-Oriented Databases �An object-oriented database (OODB) shop data in objects. �An thing is things that has data, as well as the actions that read or process the data. �OODBs can store much more types of data than relational databases, access data faster, and allow programmers come reuse objects.


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Object-Oriented Databases �A multimedia database shop images, audio clips, and/or video clip clips. ◦ Ex. Voice mail system �A groupware database stores documents such as schedules, calendars, manuals, memos, and also reports. ◦ Ex. Schedules for meeting times.


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Object-Oriented Databases �A computer-aided design (CAD) database stores data about engineering, architectural, and scientific designs. ◦ contains a perform of contents of the item gift designed, the relationship amongst components, and design drafts. �A hypertext database contains text web links to other types of documents. �A hypermedia database has text, graphics, video, and also sound.


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Object ask Language �Object-oriented and also object-relational databases frequently use a questions language called object query language (OQL) come manipulate and also retrieve data. �OQL is comparable to SQL and uses many of the very same rules, grammar, and also keywords.


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Multidimensional Databases �A multidimensional database stores data in dimensions. �Whereas a relational database is a two-dimensional table, a multidimensional database deserve to store much more than 2 dimensions the data. �These lot of dimensions, well-known as hypercube, allow users to accessibility and analyze any kind of view the the database data.


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Multidimensional Databases �The variety of dimensions varies. ◦ Ex. A retail service might have 4: products, customers, regions, and time. �Nearly every multidimensional database has actually a measurement of time. �Multidimensional databases deserve to consolidate data much quicker than a relational database.


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Data Warehouses �One applications that supplies multidimensional databases is a data warehouse, i m sorry is a vast database that stores and also manages the data required to analyze historical and current transactions. �A data warehouse typically has a userfriendly interface so users have the right to easily connect with its data.


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Data Warehouses �Data in a dispersed database exist in plenty of separate areas through a network or the Internet and is accessible through a solitary server. �Data warehouses regularly use a process called data mining to find patterns and also relationships among data. ◦ Ex. E-commerce because that customer preferences �A smaller sized version that a data warehouse, a data mart, has a database the helps a particular group or department make decisions.


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Web Databases �Much that the info on the internet exists in databases stored on the Web. �Some web databases room collaborative databases, where users store and share photos, videos, recordings, and also other an individual media v registered users. �The net page is used as the front end to the database.


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Web Database �A net database usually stays on a database server, which is a computer that stores and also provides accessibility to a database. �One type of routine that manages the sending and receiving that data between the prior end and also the database server is a CGI (Common Gateway Interface) script.


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Database administration �Managing a that company database needs a great deal of coordination. �The function of coordinating the use of the database belongs come the database analysts and administrators.


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Database design Guidelines �A very closely designed database renders it simpler for a user to query the database, change its data, and create reports. ◦ identify the objective of the database ◦ design the tables or files ◦ architecture the records and also fields because that each table ◦ determine the relationship among the tables




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Role that the Database experts and Administrators �The database analyst (DA), or data modeler, focuses on the definition and intake of data. �The DA decides ~ above the proper placement of fields, specifies the relationships among data, and also identifies users’ accessibility privileges. �The database administrator (DBA) needs a much more technical inside see of the data. �The DBA creates and maintains the data dictionary, manages protection of the database, monitors the performance of the database, and checks backup and recovery procedures.


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Role the the Employee as a User �Today, employees access databases from their office desktop computers, notebook computers, or even smart phones and other mobile devices. �Employees connect with databases related to inventory and identify new data in the database.