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  • The Fundamentals of Database

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    Hello Readers,

    These are the some important fundamentals of database.

    Entity and Entity Relationships:

    An Entity is place, question or thing for which we can gather or collect data.

    For example, we take the example of employee. Here, employee is an entity and now if we gather the data of the employee like his name, address, phone and email these are called the attributes of element.

    Element Relationship Diagram:

    It is also called as E-R Diagram. It is basically the graphical representation of the element or entity.

    Data and Database:

    Data:Data is that when we collect or gathered the data together in a significant way at this point we called as data.

    For example, In one of the organization there is employee name called John. So, the organization gather the data of John like his address, phone, email etc (is called data).

    So the John information is that:

    John is a employee with phone no.'4444444444' and he is assigned as DBA.

    Database: A database is a collection of information that is organized so that it can easily be accessed, managed, and updated.

    For example, a Telephone Diary is a database which collect the information of the people as the data like people name, phone and its address.

    Database Management System (DBMS):

    A database management system (DBMS) is system software for creating and managing databases. The DBMS provides users and programmers with a systematic way to create, retrieve, update and manage data.

    Advantages of DBMS:

    1. Controlling Redundancy
    2. Security Over Unauthorized Access
    3. Providing Persistent Storage for Database Objects
    4. Allowing Multiple User Interface
    5. Backup and Recovery

    Database Languages:

    The below are some data database language:

    1. DDL (Data Definition Language)
    2. DML (Data Manipulation Language)

    3. DCL (Data Control Language)

    4. DDL (Data Definition Language)

    Data Definition Language (DDL) statements are used to define the database structure or schema.

    Points to remember in DDL:

    1. CREATE - create is used to create objects into the database.
    2. ALTER - alter is used to alters the structure of the database.
    3. DROP - drop is used to delete the objects from the database.
    4. TRUNCATE - truncate is used to remove all records from a table, including all spaces allocated for the records are removed.
    5. RENAME - rename is used to rename an object.

    6. DML (Data Manipulation Language)

    Data Manipulation Language (DML) statements are used for managing data within schema objects.

    Points to remember in DML:

    1. SELECT - it is used to retrieve the data from the the database
    2. INSERT - it is used to insert data into a table
    3. UPDATE - it is used to update the data witin a table
    4. DELETE - deletes all records from a table, the space for the records remain
    5. DCL ( Database Control Language)

    Points to remember in DCL:

    GRANT - it is used to gives user's access privileges to database REVOKE - it is used to withdraw access privileges given with the GRANT command

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