LOG10命令格式、参数和返回值_云原生大数据计算服务 MaxCompute(MaxCompute)-阿里云帮助中心

返回以10为底，number的对数。此函数为MaxCompute 2.0扩展函数。

命令格式

double log10(<number>)

参数说明

number：必填。DOUBLE、BIGINT、INT、SMALLINT、TINYINT、FLOAT、DECIMAL、STRING类型。

返回值说明

返回DOUBLE类型。number值为0、负数或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         |
| 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NULL。
select log10(null);
--返回NULL。
select log10(0);
--返回0.9030899869919435。
select log10(8);

使用示例：表数据示例

基于示例数据，计算所有列以10为底的对数，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 log10(int_data) as int_new, log10(bigint_data) as bigint_new, log10(double_data) as double_new, log10(decimal_data) as decimal_new, log10(float_data) as float_new, log10(string_data) as string_new from mf_math_fun_t;

返回结果如下。

+--------------------+--------------------+---------------------+---------------------+-----------------------+--------------------+
| int_new            | bigint_new         | double_new          | decimal_new         | float_new             | string_new         |
+--------------------+--------------------+---------------------+---------------------+-----------------------+--------------------+
| NULL               | NULL               | -0.2798406965940431 | -0.2798406965940431 | -0.27984071631668606  | 1.0                |
| NULL               | NULL               | NULL                | NULL                | NULL                  | NULL               |
| NULL               | NULL               | NULL                | 1.3106933123433606  | NULL                  | 1.4771212547196624 |
| NULL               | 0.6020599913279623 | -0.0506099933550872 | NULL                | -0.050610000335573106 | NULL               |
| 0.6989700043360187 | NULL               | NULL                | NULL                | NULL                  | 1.6989700043360185 |
| NULL               | 0.7781512503836435 | 0.17609125905568124 | 0.17609125905568124 | 0.17609125905568124   | NULL               |
| NULL               | NULL               | NULL                | NULL                | NULL                  | NULL               |
| NULL               | 0.0                | NULL                | NULL                | NULL                  | NULL               |
| 0.9542425094393249 | NULL               | 0.4116197059632301  | 0.4116197059632301  | 0.411619693120579     | NULL               |
| NULL               | 1.0                | NULL                | NULL                | NULL                  | NULL               |
+--------------------+--------------------+---------------------+---------------------+-----------------------+--------------------+