Learn SQL :What is SQL Database , What is SQL Tables , And How it is Implemented.

Let's start with the basic things of SQL:

 SQL Database

What is Database?
  • A database is the organised collection of the data or we can say a database is a container that hold tables and other SQL structures related to those tables.

  • The main purpose of creating the database is to operate large amount of information by storing, retrieving and managing.

  • A database is generally represented by a cylindrical structure.

What are tables?


A table is the structure inside the database that contains data, organized in 'columns' and 'rows'

Roll no. Name Mobile no.
1 Aashu 81765
2 Ajeet 83567
3 Aakriti 74653

Fields : It is a small entity of the table which contain specific information about each records or  row of the table.
In above table fields are  "Roll no., Name, Mobile no."

Records or Row : It is the horizontal entity which contain specific information about each individual entry.  


1 Aashu 81765

Columns :  It is the vertical entity which contain specific information associated with the fields.


SQL Syntax:

1. SQL is not case sensitive means we can use upper and lower 
    case both. But generally the keywords or commands are written      in upper case letter

2. We can write SQL statement on one or multiple lines.

SQL commands:

  • Some of the SQL commands are:

 Command How they work
 SELECT It extracts data from a database.
 UPDATE It updates data in database.
 DELETE It deletes data from database.
 CREATE TABLE It is used to create the table.
 DROP TABLE It deletes a table.
 ALTER TABLE It is used to modify a table.
 CREATE DATABASE It creates a new database.
 ALTER DATABASE It is used to modify a database.
 INSERT INTO It inserts new data into a database.

SOL Datatypes:

Some common datatypes are:

 Integer INT It is used to specify an integer.
 Character CHAR(x) Here 'x' is  the character's number to store.
 Decimal DEC(x,y) It specify a decimal value in which 'x' is precision value and 'y' is scale value.
 VARCHAR() It holds text data both in characters and numbers.
 Blob BLOB It is same as CHAR or VARCHAR except the range of storing the text. It can hold more than 256 character.  
 Date DATETIME It is used to store future event.
 Date TIMESTAMP It is used to capture the current date

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