SQL Commands:
=============
SQL Statement:
-------------
=> also called as "SQL Query"
which we can use to interact with Oracle database software.
=> The statement is the collection or group of pre-defined words or keywords or reserved words.
Ex: select * from all_users;

Note:
-----
In SQL, we have the total of 44-keywords to use.

=> there are five types of SQL commands:
	1) DDL (Data Definition Language) Commands
	2) DML (Data Manipulation Language) Commands
	3) DCL (Data Control Language) Commands
	4) DRL/DQL (Data Retrieval Language/Data Query Language) Commands
	5) TCL (Transaction Control Language) Commands.

==> The DDL commands involve in:
	the structure of the database objects like: table, view, functions, joints etc.
That means:
	creation, modification, dropping etc.
The major DDL commands are:
	create, alter, drop etc.

==> When we need to perform the operations/actions on the data of the database objects, we can use "DML commands".
The major DML commands are:
	insert, update, delete etc.

==> DCL commands can always use by DBA (Database Admin)
for granting or revoking of permissions to the DB users.
The major DCL commands are:
	grant, revoke

==> To retrieve the data based on the condition or without condition we can use "DRL commands".
Ex: Student Table with 100's of information
from this, if I want to get the student info whose age is >= 15
=> The DRL command is "select".

==> TCL Commands are used to control the transactions.
The TCL commands are:
	1) commit
	2) rollback

==============================================

Table Database Object:
======================
1) Creation of the table object:
--------------------------------
=> by using a DDL command called "create", we can create the table.
Syntax-1:
---------
	create database-object-name <identifier-for-object>(
	);

=> to create the table:
	create table <table-name>(<col-name1> <datatype>,
	<col-name2> <datatype>,
	<col-name3> <datatype>,
	...
	....
	);

Ex: Creation of the table with the name of "customerInfo" which includes the fields like:
	1) SNO ==> number
	2) CId ==> Number
	3) CName ==> String
	4) Age ==> Number
	5) Gender ==> String
	6) Location ==> String

Syntax:
	create table customerInfo(
	SNo number(6),
	CId number(6),
	CName varchar2(50),
	Age number(3),
	Gender varchar(15),
	Location varchar2(50));

Rules for Identifiers:
=====================
1) Identifier must be start with alphabets only.
2) Allowed character set for identifier are:
	alphabets, digits, special characters (@, #, $, _)
3) Identifier never be the reserved word.
4) No space is allowed in the identifier.