How to use Row_number() over() in Oracle database

1. Raw data (partial)

SELECT * FROM SCOTT.EMP ; 

2. Use the Row_number() over() function to sort

SELECT EMPNO,ENAME,SAL,DEPTNO,Row_number() over( order by sal) rs FROM SCOTT.EMP ;

Sort by salary and add sequence number

3. Use the Row_number() over() function to group and sort

SELECT EMPNO,ENAME,SAL,DEPTNO,Row_number() over(partition by DEPTNO order by sal) rs FROM SCOTT.EMP;