Index is a schema object which contains an entry for each value that appears in the indexed column(s) of the table or cluster. Index provides direct, fast access to rows.

CREATE TABLE MYEmp
AS SELECT * FROM Emp;

Table created.


DESC MYEmp
 Name                     Null?    Type
 ------------------------ -------- -----------------
 EMPNO                             NUMBER(4)
 ENAME                             VARCHAR2(10)
 JOB                               VARCHAR2(9)
 MGR                               NUMBER(4)
 HIREDATE                          DATE
 SAL                               NUMBER(7,2)
 COMM                              NUMBER(7,2)
 DEPTNO                            NUMBER(2)


CREATE INDEX Idx_MYEmp_Empno
ON MYEmp(Empno);

Index created.