OceanBase 中标准差的值是函数 VARIANCE
计算出的方差的算术平方根。
作为分析函数使用时,您需要使用窗口函数的完整语法,它对一组行的集合进行计算并返回多个值 。作为聚合函数使用时,该函数对一组行的集合进行聚合计算,结果只能返回一个值,此时不需要加 OVER
关键字。
注意
返回 NUMBER
类型数据。
分析函数示例
以下语句创建了表 employees,并向里面插入数据
INSERT INTO employees VALUES(100, 'Raphaely', '2017-07-01', 1700);
INSERT INTO employees VALUES(100, 'De Haan', '2018-05-01',11000);
INSERT INTO employees VALUES(100, 'Errazuriz', '2017-07-21', 1400);
INSERT INTO employees VALUES(100, 'Hartstein', '2019-05-01',14000);
INSERT INTO employees VALUES(100, 'Raphaely', '2017-07-22', 1700);
INSERT INTO employees VALUES(100, 'Weiss', '2019-07-11',13500);
INSERT INTO employees VALUES(100, 'Partners', '2018-12-01',14000);
INSERT INTO employees VALUES(200, 'Ross', '2019-06-11',13500);
INSERT INTO employees VALUES(200, 'Bell', '2019-05-25', 13000);
INSERT INTO employees VALUES(200, 'Part', '2018-08-11',14000);
COMMIT;
调用函数并执行以下语句:
查询结果如下:
+-----------+--------+-------------------------------------------+
+-----------+--------+-------------------------------------------+
| De Haan | 11000 | 4702.127178203498995615489088200868644482 |
| Errazuriz | 1400 | 212.132034355964257320253308631454711785 |
| Partners | 14000 | 6064.899009876421676804205219406952308814 |
| Raphaely | 1700 | 0 |
| Raphaely | 1700 | 173.205080756887729352744634150587236694 |
| Russell | 13000 | 6026.474330580265330900400184969999384459 |
| Weiss | 13500 | 6244.311697171159907069428668980211861012 |
+-----------+--------+-------------------------------------------+
聚合函数示例
调用函数并执行以下语句:
+-------------------------------------------+
| STDDEV(SALARY) |
+-------------------------------------------+