A web database usually resides on a database server

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

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Database management Systems

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

Data thesaurus �Because the data dictionary contains details about data, some speak to it metadata, meta definition more comprehensive. �It is a crucial backbone come a DBMS therefore only expert professionals must update that is contents. �It is provided to perform validation checks and limit the type of data that can be entered.

Data dictionary �A data dictionary permits users to specify a default value for a field, i m sorry is a value 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 to kind the default value which help in to reduce errors.

Data dictionary

File Retrieval and Maintenance �A DBMS offers several tools that allow users and also programs to retrieve and maintain data in the database (adding, modifying, and also deleting). �To retrieve or pick data in a database, girlfriend query it, which is a request for details data native the database. �Users deserve to instruct the DBMS come display, print, or keep the results of a query, make it one of the an ext powerful database features.

Query Language �A query language is composed of simple, English-like explanation that allow users to specify the data to display, print, or store. �Each has actually its own grammar and vocabulary. �A human being without programming experience can learn a query language in a brief time. �Most queries are offered to retrieve data. �Some DBMSs provide wizards to overview

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

Form �A form, sometimes referred to as a data entry form, is a home window on the display that provides locations for start or editing data in a database. �Well-designed creates should validate data together it is entered. �A type that sends gotten in data throughout a network or the web is called an eform, short for digital form. �E-forms normally use a way to for sure the data while that is transported throughout the network.

Form

Report Generator �A report generator, additionally called a report writer, permits users to style a report on the screen, retrieve data right into the report design, and then display or print the report. �Unlike a form, report generators can only retrieve data. �Report generators allow you to style the page and some allow you to create a report together a net page.

Report Generator

Data protection �A DBMS provides way to ensure that only authorized users can access data at permitted times. �Most DBMSs enable different level of access privileges to be identified for each field in the database, defining the actions that a details user or group can perform.

Data security �Access privileges for data involve establishing who can enter brand-new data, change existing data, delete unwanted data, and also view data. ◦ Ex. A college student would have actually read-only privileges: enabling them to see the perform of readily available classes but not adjust them. ◦ Ex. A room head would be able to modify the data. ◦ Ex. Various other users would have actually no access privileges come the data.

Data security �Many organizations adopt a principle of least privilege policy, whereby users’ access privileges are limited to the shortest level crucial to perform required tasks.

Backup and Recovery �Occasionally a database is damaged or destroyed, so a DBMS offers a range of techniques to restore the database come a usable form. �A backup, or copy, the the entire database need to be made on a continuous basis. �Some DBMSs have a built-in backup utility while others need a different utility.

Backup and also Recovery �More facility DBMSs maintain a log, which is a listing of tasks that change the materials of the database. ◦ Ex. A registration clerk modifies a student’s address, the adjust will show up in the log. �The log in contains: ◦ A copy of the record prior to the readjust called the before image ◦ The readjust being make ◦ and also a copy that the document after the readjust called the after image ◦ The log in may additionally store that made the readjust and when.

Backup and also Recovery �DBMSs that produce logs usually provide a recovery unit, which supplies the logs and/or backups to regain a database when it i do not care damaged or ruined using rollforward and also rollback techniques. �In a rollforward, or forward recovery, the DBMS offers the log to reenter transforms made to the database due to the fact that the last save or backup. �In a rollback, or behind recovery, the DBMS offers the log in to undo any changes made to the database during a details

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

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

Relational, Object-Oriented, and also Multidimensional Databases �Three renowned data models in usage today are relational, object-oriented, and multidimensional. �Some are dubbed object-relational databases since they integrate features of the relational and also objectoriented data models.

Relational Databases �A relational database is a database the stores data in tables the consist the rows and columns. �Each row has actually a primary crucial and each column has actually a unique name. �A developer that a relational database refers to a file as a relation, a record as a tuple, and also a field as an attribute.

Relational Databases �A user the a relational database refers to a document as a table, a record as a row, and also a field as a column. �In enhancement to save data, a relational database likewise stores data relationships, i m sorry are links within the data. �With a relational database, girlfriend can collection up a relationship between tables with typical fields.

Relational Databases

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

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

Object-Oriented Databases �An object-oriented database (OODB) stores data in objects. �An object is an object that includes data, and the plot that check out or process the data. �OODBs have the right to store much more types of data 보다 relational databases, access data faster, and allow programmers to reuse objects.

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

Object-Oriented Databases �A computer-aided architecture (CAD) database stores data around engineering, architectural, and scientific designs. ◦ includes a perform of materials of the item being designed, the relationship amongst components, and also design drafts. �A hypertext database consists of text web links to other varieties of documents. �A hypermedia database has text, graphics, video, and also sound.

Object questions Language �Object-oriented and object-relational databases often use a query language referred to as object query language (OQL) to manipulate and retrieve data. �OQL is similar to SQL and also uses countless of the exact same rules, grammar, and keywords.

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

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

Data Warehouses �One applications that supplies multidimensional databases is a data warehouse, which is a huge database that stores and also manages the data compelled to analyze historical and also current transactions. �A data warehouse commonly has a userfriendly user interface so users can easily interact with that data.

Data Warehouses �Data in a spread database exist in plenty of separate areas through a network or the Internet and is available through a single server. �Data warehouses frequently use a procedure called data mining to find patterns and relationships amongst 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 details group or department make decisions.

Web Databases �Much that the information on the web exists in databases save on the Web. �Some net databases are collaborative databases, where customers store and share photos, videos, recordings, and also other personal media with registered users. �The net page is offered as the front finish to the database.

Web Database �A internet database usually lives on a database server, i beg your pardon is a computer that stores and also provides access to a database. �One kind of routine that manages the sending and receiving that data in between the former end and also the database server is a CGI (Common Gateway Interface) script.

Database management �Managing a company’s database requires a good deal of coordination. �The duty of coordinating the use of the database belongs to the database experts and administrators.

Database style Guidelines �A closely designed database renders it simpler for a user come query the database, modify its data, and create reports. ◦ recognize the function of the database ◦ architecture the tables or documents ◦ style the records and also fields because that each table ◦ identify the relationship among the tables

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Role of the Database analysts and Administrators �The database analyst (DA), or data modeler, concentrates on the meaning and usage of data. �The DA decides top top the suitable placement that fields, defines the relationships amongst data, and identifies users’ access privileges. �The database administrator (DBA) requires a an ext technical inside view of the data. �The DBA creates and maintains the data dictionary, manages defense of the database, monitors the performance of the database, and also checks backup and recovery procedures.

Role of the Employee as a User �Today, employees accessibility databases from their office desktop computers, notebook computers, or also smart phones and other mobile devices. �Employees interact with databases related to inventory and also identify brand-new data in the database.