计算number的立方根。此函数为MaxCompute 2.0扩展函数。
命令格式
double cbrt(<number>)参数说明
number：必填。支持BIGINT、INT、SMALLINT、TINYINT、DOUBLE、FLOAT、STRING类型数值。
返回值说明
返回DOUBLE类型。返回规则如下：
number不是BIGINT、INT、SMALLINT、TINYINT、DOUBLE、FLOAT以及STRING类型时，返回报错。
number值为NULL时，返回NULL。
示例数据
为便于理解各函数的使用方法，本文为您提供源数据，基于源数据提供函数相关示例。创建表mf_math_fun_t，并添加数据，命令示例如下。
CREATE TABLE IF NOT EXISTS mf_math_fun_t(
int_data INT,
bigint_data BIGINT,
double_data DOUBLE,
decimal_data DECIMAL,
float_data FLOAT,
string_data STRING
);
INSERT INTO mf_math_fun_t VALUES
(null, -10, 0.525, 0.525BD, CAST(0.525 AS FLOAT), '10'),
(-20, null, -0.1, -0.1BD, CAST(-0.1 AS FLOAT), '-10'),
(0, -1, null, 20.45BD, CAST(-1 AS FLOAT), '30'),
(-40, 4, 0.89, null, CAST(0.89 AS FLOAT), '-30'),
(5, -50, -1, -1BD, null, '50'),
(-60, 6, 1.5, 1.5BD, CAST(1.5 AS FLOAT), '-50'),
(-1, -70, -7.5, -7.5BD, CAST(-7.5 AS FLOAT),null ),
(-80, 1, -10.2, -10.2BD, CAST(-10.2 AS FLOAT), '-1' ),
(9, -90, 2.58, 2.58BD, CAST(2.58 AS FLOAT), '0'),
(-100, 10, -5.8, -5.8BD, CAST(-5.8 AS FLOAT), '-90');查询表mf_math_fun_t中的数据，命令示例如下：
SELECT * FROM mf_math_fun_t;
--返回结果。
+------------+-------------+-------------+--------------+------------+-------------+
| int_data | bigint_data | double_data | decimal_data | float_data | string_data |
+------------+-------------+-------------+--------------+------------+-------------+
| NULL | -10 | 0.525 | 0.525 | 0.525 | 10 |
| -20 | NULL | -0.1 | -0.1 | -0.1 | -10 |
| 0 | -1 | NULL | 20.45 | -1.0 | 30 |
| -40 | 4 | 0.89 | NULL | 0.89 | -30 |
| 5 | -50 | -1.0 | -1 | NULL | 50 |
| -60 | 6 | 1.5 | 1.5 | 1.5 | -50 |
| -1 | -70 | -7.5 | -7.5 | -7.5 | NULL |
| -80 | 1 | -10.2 | -10.2 | -10.2 | -1 |
| 9 | -90 | 2.58 | 2.58 | 2.58 | 0 |
| -100 | 10 | -5.8 | -5.8 | -5.8 | -90 |
+------------+-------------+-------------+--------------+------------+-------------+使用示例：静态数据示例
--返回2.0。
select cbrt(8);
--返回NULL。
select cbrt(null);使用示例：表数据示例
基于示例数据，获取除decimal_data之外其他列的立方根，命令示例如下。
--开启2.0新类型。此命令需要与SQL语句一起提交。
set odps.sql.type.system.odps2=true;
select cbrt(int_data) as int_new, cbrt(bigint_data) as bigint_new, cbrt(double_data) as double_new, cbrt(float_data) as float_new, cbrt(string_data) as string_new from mf_math_fun_t;返回结果如下。
+---------------------+---------------------+----------------------+---------------------+---------------------+
| int_new | bigint_new | double_new | float_new | string_new |
+---------------------+---------------------+----------------------+---------------------+---------------------+
| NULL | -2.1544346900318834 | 0.806714323012272 | 0.8067143108004823 | 2.1544346900318834 |
| -2.7144176165949063 | NULL | -0.46415888336127786 | -0.46415888566678 | -2.1544346900318834 |
| 0.0 | -1.0 | NULL | -1.0 | 3.107232505953859 |
| -3.4199518933533937 | 1.5874010519681996 | 0.9619001716077046 | 0.961900166454112 | -3.107232505953859 |
| 1.7099759466766968 | -3.6840314986403864 | -1.0 | NULL | 3.6840314986403864 |
| -3.9148676411688634 | 1.8171205928321394 | 1.1447142425533317 | 1.1447142425533317 | -3.6840314986403864 |
| -1.0 | -4.121285299808557 | -1.9574338205844317 | -1.9574338205844317 | NULL |
| -4.308869380063767 | 1.0 | -2.168702885250197 | -2.1687028717323127 | -1.0 |
| 2.080083823051904 | -4.481404746557165 | 1.3715339700741747 | 1.3715339565548288 | 0.0 |
| -4.641588833612778 | 2.1544346900318834 | -1.7967017791430528 | -1.7967017988380907 | -4.481404746557165 |
+---------------------+---------------------+----------------------+---------------------+---------------------+相关函数
CBRT函数属于数学函数，更多数据计算、数据转换的相关函数请参见数学函数。