Below are the examples of CREATE INDEX in Oracle.
Create a Unique Index
In the following example, it will create a unique index on the EMP table for column EMPNO.
CREATE UNIQUE INDEX emp_unique_index ON EMP (EMPNO) /
Create a Non-Unique Index
In the following example, it will create a non-unique index on the EMP table for columns EMPNO, ENAME, and JOB.
CREATE INDEX emp_nonunique_index ON EMP (EMPNO, ENAME, JOB) /