/* Formatted on 5/24/2012 4:15:58 PM (QP5 v5.149.1003.31008) */

SELECT deptno,

      ename,                     --st_name || ' ' || last_name employee_name,

      hiredate,

     sal,

       STDDEV (sal) OVER (PARTITION BY deptno ORDER BY hiredate) AS "STDDEV", --标准差

       STDDEV_SAMP (sal) OVER (PARTITION BY deptno ORDER BY hiredate)

          AS "STDDEV_SAMP",                                            --样本标准差

       VAR_POP (sal) OVER (PARTITION BY deptno ORDER BY hiredate)    说明：VAR_POP 为函数， sal为要求的数据列，  以‘deptno’为分组的根据，即满足这个条件下才进行方差的操作，最后根据‘hiredate’进行排序。

          AS "VAR_POP",                                                   --方差

       VAR_SAMP (sal) OVER (PARTITION BY deptno ORDER BY hiredate)

          AS "VAR_SAMP"                                                 --样本方差

  FROM scott.emp

 WHERE deptno IN (20);

 

 /* Formatted on 5/24/2012 4:15:58 PM (QP5 v5.149.1003.31008) */

SELECT deptno,

       STDDEV (sal)  AS "STDDEV", --标准差

       STDDEV_SAMP (sal)

          AS "STDDEV_SAMP",                                            --样本标准差

       VAR_POP (sal)

          AS "VAR_POP",                                                   --方差

       VAR_SAMP (sal)

          AS "VAR_SAMP"                                                 --样本方差

  FROM scott.emp

group  by deptno