Analytical function of oracle function

1. The parsing function has four over row_number dense_rank rank and four cannot be used alone.

2.select empno, sal, deptno,sum (sal) over (order by empno), sum (sal) over () from emp; views are as follows: add up by salary

3 select empno, sal, deptno

Sum (sal) over (partition by deptno)-- the sum of each department

Sum (sal) over (order by deptno)-- summation of departments

Sum (sal) over (partition by deptno order by empno)-- first divided into departments and then accumulated under their respective departments

Sum (sal) over ()

The from emp; view is as follows

4 select empno,deptno,ename

Row_number () over (order by deptno)-- increase the serial number in sequence according to the department number

Dense_rank () over (order by deptno),-- the root department number is sorted strictly according to size and can be juxtaposed.

Rank () over (order by deptno)-- the root department number is sorted strictly according to size, but it can be juxtaposed, but there will be a jump mark that should not be occupied by the other two 1s, which is directly 4.

From emp;-- order by can be followed by desc in descending order

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