When an index is created by using multiple columns then it is known as Composite index .
• Create an index on the NAME AND SALARY columns of the employees table.
SQL) CREATE INDEX RAMAN_DHILLON
2 ON EMPlOYEES (NAME,SAlARY);
• Create a Unique Composite Index on NAME and SALARY.
SQL> CREATE UNIQUE INDEX RAMAN_DHILLION
2 ON EMPlOYEES(NAME,SALARY);