Oracle SQL - Function VARIANCE function

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Introduction

VARIANCE function gives the variance of all values of a group of rows.

The general format for this function is: 

VARIANCE([DISTINCT |ALL] expr)

Demo

SQL>
SQL>-- from  www.  ja  v a  2s  .  c o  m
SQL> SELECT VARIANCE (DISTINCT(y)) FROM my_table;

VARIANCE(DISTINCT(Y))
---------------------
             75434.62

SQL>

Given the following table.

Demo

SQL>
SQL> drop table my_table;

Table dropped.-- ww w . j a v  a2 s  .  c o m

SQL> create table my_table(
  2  x      NUMBER(4)  primary key,
  3  y      NUMBER(4)  not null);
SQL>
SQL> insert into my_table values(1,2);
SQL> insert into my_table values(2,4);
SQL> insert into my_table values(3,6);
SQL> insert into my_table values(4,9);
SQL> insert into my_table values(5,13);
SQL> insert into my_table values(6,16);
SQL> insert into my_table values(7,20);
SQL> insert into my_table values(8,27);
SQL> insert into my_table values(9,32);
SQL> insert into my_table values(10,47);
SQL> insert into my_table values(11,53);
SQL> insert into my_table values(12,60);
SQL> insert into my_table values(13,76);
SQL> insert into my_table values(14,100);
SQL> insert into my_table values(15,130);
SQL> insert into my_table values(16,189);
SQL> insert into my_table values(17,300);
SQL> insert into my_table values(18,789);
SQL> insert into my_table values(19,1000);
SQL>