Oracle SQL - STDDEV_SAMP function

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Introduction

STDDEV_SAMP function computes the cumulative sample standard deviation.

It gives the square root of the sample variance.

The general format for this function is: 

STDDEV_SAMP(expr) [OVER(analytic_clause)]

Demo

SQL>
SQL>--  w  w  w  . j  a  v  a  2  s.  com
SQL> SELECT STDDEV_SAMP(y) FROM my_table;

STDDEV_SAMP(Y)
--------------
      00274.65

SQL>

Given the following table.

Demo

SQL>
SQL> drop table my_table;

Table dropped.--   ww w . j av  a 2 s .c  om

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>