Oracle SQL - Partitioning with PARTITION_BYPARTITION_BY

Introduction

Partitioning separates groupings of data and performs a function from within that group.

The following code shows how to partition the data to look at salaries within each region.

To do this we use a partition analytical clause in the analytical function like this:

Demo

SQL>
SQL> drop table emp;

Table dropped.--  w w  w  .j av a  2  s.c o  m

SQL> create table emp(
  2  empno        Number(3)  NOT NULL,
  3  ename        VARCHAR2(10 BYTE),
  4  hireDate     DATE,
  5  orig_salary  Number(8,2),
  6  curr_salary  Number(8,2),
  7  region       VARCHAR2(1 BYTE)
  8  );
SQL>
SQL> insert into emp values(1,'Alison',DATE '1996-03-21', 45000, NULL,  'E');
SQL> insert into emp values(2,'James',DATE  '1978-12-12', 23000, 32000, 'W');
SQL> insert into emp values(3,'Celia',DATE  '1982-10-24', NULL,  58000, 'E');
SQL> insert into emp values(4,'Robert',DATE '1984-01-15', 31000, NULL,  'W');
SQL> insert into emp values(5,'Linda',DATE  '1987-07-30', NULL,  53000, 'E');
SQL> insert into emp values(6,'David',DATE  '1990-12-31', 78000, NULL,  'W');
SQL> insert into emp values(7,'Jode',DATE  '1996-09-17', 21000, 29000, 'E');
SQL>
SQL> SELECT empno, ename, region, curr_salary,
  2    RANK() OVER(PARTITION BY region ORDER BY curr_salary desc)
  3        rank
  4  FROM emp
  5  ORDER BY region
  6

PARTITION BY phrase must precede the ORDER BY phrase.

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