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Database Related Post

What Is DataBase ? | Use Of It | Example Of Database

Upload time : 2018-09-14 02:41:46

Category : Database Related


Often We Listen That Database Of This Website Was hacked.So What Is Database?


- Database is a repository or collection of logically related, and similar data. Database stores similar kind of data that is organized in a manner that the information can be derived from it, modified, data added, or deleted to it, and used when needed.

- Some examples of databases in real life situations are:

  • dictionary a database of words organized alphabetically along with their meaning.
  • telephone directory—a database of telephone numbers and addresses organized by the last name of people.
  • railway timetable a database of trains organized by train names, and, companies listed on Stock Exchange organized by names alphabetically.

    - A database is defined as a collection, or repository of data, (2) having an organized structure, and (3) for a specific purpose. A database stores information, which is useful to an organization. It contains data based on the kind of application for which it is required.

    For example

  • An airline database may contain data about the airplane, the routes, airline reservation, airline schedules etc.
  • A college database may contain data about the students, faculty, administrative staff, courses, results etc.
  • A database for manufacturing application may contain data about the production, inventory, supply chain, orders, sales etc.
  • A student database may contain data about students, like student names, student course etc.

  • There Are Many Database like

  • Mysql Database
  • Sql Database
  • Mongo DB
  • JSON Format

  • So..

    Introduction RDBMS : E.F. Codd's 12 Rule, DBMS vs. RDBMS

    Upload time : 2019-03-14 11:44:28

    Category : Database Related


    - Relational Database Management System

    - For defining a fully relational database
    - Dr. E. F. Codd 12 rules is used.
    - Codd twelve rules are a set of thirteen rules (numbered zero to twelve) proposed by Edgar F. Codd, a pioneer of the relational model for databases.
    - Codd Rule Designed to define what is required from a database management system in order for it to be considered relational.

    Rule 1: The Information Rule

    - All data should be presented to the user in table form.

    Rule 2: Guaranteed Access Rule

    - All data should be accessible without ambiguity.

    - This can be achieved through a combination of the table name, primary key, and column name.

    Rule 3: Systematic Treatment of Null Values

    - A field should be allowed to remain empty. - This involves the support of a null value, which is distinct from an empty string or a number with a value of zero.

    - Of course, this can't apply to primary keys.

    Rule 4: Active online catalog based on the relational model

    - The system must support an online, inline, relational catalog that is accessible to authorized users by means of their regular query language.

    - Users must be able to access the database's structure (catalog) using the same query language that they use to access the database's data.

    Rule 5: Comprehensive Data Sublanguage

    - The database must support at least one clearly defined language that includes functionality for data definition, data manipulation, data integrity, and database transaction control.

    - All commercial relational databases use forms of the standard SQL (Structured Query Language) as their supported comprehensive language.

    - Supported Language :
    - Data definition
    - View definition
    - Data manipulation (interactive and by program)
    - Integrity constraints
    - Authorization
    - Transaction boundaries (begin, commit, and rollback).

    Rule 6: View Updating Rule

    - View : Data can be presented to the user in different logical combinations, called views.

    - Each view should support the same full range of data manipulation that direct-access to a table has available.

    Rule 7: High-level Insert, Update, and Delete

    - The system must support set-at-a-time insert, update, and delete operators.

    - This means that data can be retrieved from a relational database in sets constructed of data from multiple rows and/or multiple tables.

    Rule 8: Physical Data Independence

    - Changes to the physical level (how the data is stored, whether in arrays or linked lists etc.) must not require a change to an application based on the structure.

    Rule 9: Logical Data Independence

    - Changes to the logical level (tables, columns, rows, and so on) must not require a change to an application based on the structure.

    - Logical data independence is more difficult to achieve than physical data independence

    Rule 10: Integrity Independence

    - Integrity constraints must be specified separately from application programs and stored in the structure/catalog.

    - No component of a primary key can have a null value. (see rule 3) If a foreign key is defined in one table, any value in it must exist as a primary key in another table.

    - Key and Check constraints, trigger etc should be stored in Data Dictionary.

    Rule 11: Distribution Independence

    - A user should be totally unaware of whether or not the database is distributed (whether parts of the database exist in multiple locations).

    - A variety of reasons make this rule difficult to implement;

    Rule 12: Non subversion Rule

    - If a relational system has or supports a low-level (single-recordat-a-time) language, that low-level language cannot be used to subvert or bypass the integrity rules or constraints expressed in the higher-level (multiple-records-at-a-time) relational language.

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