VARIANCE
Calculates the variance of the specified column.
Example:
Calculates the variance of sa1.
SELECT empno, sal, VARIANCE(sal) OVER (ORDER BY hiredate) "Variance" FROM emp ORDER BY ename, sal, "Variance"; EMPNO | SAL | Variance -------+-------+------------------------ 7876 | 8100 | 2999125 7499 | 7600 | 2080000 7698 | 11850 | 5697604.166666666667 7782 | 7450 | 4749315.47619047619 7902 | 8000 | 3630961.174242424242 7900 | 5950 | 3630961.174242424242 7566 | 7975 | 1564250 7839 | 10000 | 4143673.611111111111 7654 | 6250 | 3826250 7934 | 6300 | 3430480.769230769231 7788 | 8000 | 3195539.148351648352 7469 | 4800 | 2000000 7369 | 6800 | 2000000 7844 | 6500 | 4204006.696428571429 7521 | 6250 | 1392291.666666666667 (15 rows) CORR
Calculate the correlation coefficient of a pair of expressions.
Example:
postgres=# select corr(t.num,test.num) from postgres-# (select id-1 as id, num from test) as t,test where t.id=test.id ; CORR(T.NUM,TEST.NUM) ------------------------------ -0.7802897838627655 (1 row) 
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