Explain Plan 

#1

	SET AUTOT ON 
	SET AUTOTRACE TRACEONLY

#2

	EXPLAIN PLAN FOR
       SELECT * FROM departments;

        Explained.

       SELECT * FROM TABLE(dbms_xplan.display());

#3  SQL Developer  (F10 )

#4  Plsql Developer ( F5 )


Index ( _ind )
	One of the Performance Tuning Method  | 60%
	It is a Schema Object 

	user_indexes | user_ind_columns 

Types of Index 
	Uniqu  Index
		-- while creating PK and UK 
	Non  Unique  Index
	      -- We need to Create It 

		B-Tree Index  (Default)
		Bitmap Index
		Function Based Index
		Reverse Key Index
		Clustered Index  / Non Clustered Index
		IOT
		 
-->-- B-Tree Index  (Default)

CREATE  INDEX id_ind  ON employees(employee_id);

-->-- Bitmap Index

CREATE  BITMAP INDEX gen_ind  ON employees(gender);

-->-- Function Based Index 

CREATE  INDEX fname1_ind  ON employees(LOWER(first_name));
CREATE  INDEX sal_ind  ON employees(salary*12);

SELECT * FROM employees WHERE LOWER(first_name) = LOWER('STEVEN');

CREATE  INDEX id_ind  ON employees(emp_marks) REVERSE;

DROP TABLE temployees;

CREATE TABLE temployees AS SELECT * FROM employees;

SELECT * FROM user_indexes WHERE table_name = UPPER('temployees');
SELECT * FROM user_ind_columns WHERE table_name = UPPER('temployees');

ALTER TABLE temployees ADD CONSTRAINT pk_eid_cons PRIMARY KEY(employee_id);

CREATE INDEX did_ind ON temployees(department_id);