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首页 云原生大数据计算服务 MaxCompute 操作指南 开发参考：SQL 函数参考 内建函数（字母排序） EXTRACT

EXTRACT

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提取日期date中指定单位datepart的部分。此函数为MaxCompute 2.0扩展函数。

命令格式

int extract(<datepart> from date|datetime|timestamp <date>)

参数说明

  • datepart：必填。支持YEAR、MONTH、DAY、HOUR或MINUTE等时间取值。

  • date：必填。DATE、DATETIME、TIMESTAMP或STRING类型日期值，格式为yyyy-mm-dd、yyyy-mm-dd hh:mi:ss或yyyy-mm-dd hh:mi:ss.ff3。取值为STRING类型格式时，至少要包含yyyy-mm-dd且不含多余的字符串。

返回值说明

返回INT类型。返回规则如下：

  • datepart非YEAR、MONTH、DAY、HOUR或MINUTE等时间取值时，返回报错。

  • datepart值为NULL时，返回报错。

  • date非DATE、DATETIME、TIMESTAMP或STRING类型或为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_date_fun_t，并添加数据，命令示例如下。

create table if not exists mf_date_fun_t(
    id      int,
    date1   date,
    datetime1   datetime,
    timestamp1 timestamp,
    date2   date,
    datetime2   datetime,
    timestamp2 timestamp,
    date3 string,
    date4 bigint);
insert into mf_date_fun_t values
(1,DATE'2021-11-29',DATETIME'2021-11-29 00:01:00',TIMESTAMP'2021-01-11 00:00:00.123456789',DATE'2021-10-29',DATETIME'2021-10-29 00:00:00',TIMESTAMP'2021-10-11 00:00:00.123456789','2021-11-20',123456780),
(2,DATE'2021-11-28',DATETIME'2021-11-28 00:02:00',TIMESTAMP'2021-02-11 00:00:00.123456789',DATE'2021-10-29',DATETIME'2021-10-29 00:00:00',TIMESTAMP'2021-10-11 00:00:00.123456789','2021-11-21',123456781),
(3,DATE'2021-11-27',DATETIME'2021-11-27 00:03:00',TIMESTAMP'2021-03-11 00:00:00.123456789',DATE'2021-10-29',DATETIME'2021-10-29 00:00:00',TIMESTAMP'2021-10-11 00:00:00.123456789','2021-11-22',123456782),
(4,DATE'2021-11-26',DATETIME'2021-11-26 00:04:00',TIMESTAMP'2021-04-11 00:00:00.123456789',DATE'2021-10-29',DATETIME'2021-10-29 00:00:00',TIMESTAMP'2021-10-11 00:00:00.123456789','2021-11-23',123456783),
(5,DATE'2021-11-25',DATETIME'2021-11-25 00:05:00',TIMESTAMP'2021-05-11 00:00:00.123456789',DATE'2021-10-29',DATETIME'2021-10-29 00:00:00',TIMESTAMP'2021-10-11 00:00:00.123456789','2021-11-24',123456784),
(6,DATE'2021-11-24',DATETIME'2021-11-24 00:06:00',TIMESTAMP'2021-06-11 00:00:00.123456789',DATE'2021-10-29',DATETIME'2021-10-29 00:00:00',TIMESTAMP'2021-10-11 00:00:00.123456789','2021-11-25',123456785),
(7,DATE'2021-11-23',DATETIME'2021-11-23 00:07:00',TIMESTAMP'2021-07-11 00:00:00.123456789',DATE'2021-10-29',DATETIME'2021-10-29 00:00:00',TIMESTAMP'2021-10-11 00:00:00.123456789','2021-11-26',123456786),
(8,DATE'2021-11-22',DATETIME'2021-11-22 00:08:00',TIMESTAMP'2021-08-11 00:00:00.123456789',DATE'2021-10-29',DATETIME'2021-10-29 00:00:00',TIMESTAMP'2021-10-11 00:00:00.123456789','2021-11-27',123456787),
(9,DATE'2021-11-21',DATETIME'2021-11-21 00:09:00',TIMESTAMP'2021-09-11 00:00:00.123456789',DATE'2021-10-29',DATETIME'2021-10-29 00:00:00',TIMESTAMP'2021-10-11 00:00:00.123456789','2021-11-28',123456788),
(10,DATE'2021-11-20',DATETIME'2021-11-20 00:10:00',TIMESTAMP'2021-10-11 00:00:00.123456789',DATE'2021-10-29',DATETIME'2021-10-29 00:00:00',TIMESTAMP'2021-10-11 00:00:00.123456789','2021-11-29',123456789);

查询表mf_date_fun_t中的数据，命令示例如下：

select * from mf_date_fun_t;
--返回结果。
+------------+------------+---------------------+-------------------------+------------+---------------------+-------------------------+------------+------------+
| id         | date1      | datetime1           | timestamp1              | date2      | datetime2           | timestamp2              | date3      | date4      |
+------------+------------+---------------------+-------------------------+------------+---------------------+-------------------------+------------+------------+
| 1          | 2021-11-29 | 2021-11-29 00:01:00 | 2021-01-11 00:00:00.123 | 2021-10-29 | 2021-10-29 00:00:00 | 2021-10-11 00:00:00.123 | 2021-11-20 | 123456780  |
| 2          | 2021-11-28 | 2021-11-28 00:02:00 | 2021-02-11 00:00:00.123 | 2021-10-29 | 2021-10-29 00:00:00 | 2021-10-11 00:00:00.123 | 2021-11-21 | 123456781  |
| 3          | 2021-11-27 | 2021-11-27 00:03:00 | 2021-03-11 00:00:00.123 | 2021-10-29 | 2021-10-29 00:00:00 | 2021-10-11 00:00:00.123 | 2021-11-22 | 123456782  |
| 4          | 2021-11-26 | 2021-11-26 00:04:00 | 2021-04-11 00:00:00.123 | 2021-10-29 | 2021-10-29 00:00:00 | 2021-10-11 00:00:00.123 | 2021-11-23 | 123456783  |
| 5          | 2021-11-25 | 2021-11-25 00:05:00 | 2021-05-11 00:00:00.123 | 2021-10-29 | 2021-10-29 00:00:00 | 2021-10-11 00:00:00.123 | 2021-11-24 | 123456784  |
| 6          | 2021-11-24 | 2021-11-24 00:06:00 | 2021-06-11 00:00:00.123 | 2021-10-29 | 2021-10-29 00:00:00 | 2021-10-11 00:00:00.123 | 2021-11-25 | 123456785  |
| 7          | 2021-11-23 | 2021-11-23 00:07:00 | 2021-07-11 00:00:00.123 | 2021-10-29 | 2021-10-29 00:00:00 | 2021-10-11 00:00:00.123 | 2021-11-26 | 123456786  |
| 8          | 2021-11-22 | 2021-11-22 00:08:00 | 2021-08-11 00:00:00.123 | 2021-10-29 | 2021-10-29 00:00:00 | 2021-10-11 00:00:00.123 | 2021-11-27 | 123456787  |
| 9          | 2021-11-21 | 2021-11-21 00:09:00 | 2021-09-11 00:00:00.123 | 2021-10-29 | 2021-10-29 00:00:00 | 2021-10-11 00:00:00.123 | 2021-11-28 | 123456788  |
| 10         | 2021-11-20 | 2021-11-20 00:10:00 | 2021-10-11 00:00:00.123 | 2021-10-29 | 2021-10-29 00:00:00 | 2021-10-11 00:00:00.123 | 2021-11-29 | 123456789  |
+------------+------------+---------------------+-------------------------+------------+---------------------+-------------------------+------------+------------+

使用示例：静态数据示例

--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  extract(year from '2019-05-01 11:21:00') year
         ,extract(month from '2019-05-01 11:21:00') month
         ,extract(day from '2019-05-01 11:21:00') day
         ,extract(hour from '2019-05-01 11:21:00') hour
         ,extract(minute from '2019-05-01 11:21:00') minute;
--返回值如下。
+------+-------+------+------+--------+
| year | month | day  | hour | minute |
+------+-------+------+------+--------+
| 2019 | 5     | 1    | 11   | 21     |
+------+-------+------+------+--------+
--返回NULL。
select  extract(year from null);

使用示例：表数据示例

基于示例数据，提取timestamp1列的指定部分，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 timestamp1, extract(year from timestamp1) year, timestamp2, extract(month from timestamp2) month from mf_date_fun_t;

返回结果如下。

+-------------------------------+------+-------------------------------+-------+
| timestamp1                    | year | timestamp2                    | month |
+-------------------------------+------+-------------------------------+-------+
| 2021-01-11 00:00:00.123456789 | 2021 | 2021-10-11 00:00:00.123456789 | 10    |
| 2021-02-11 00:00:00.123456789 | 2021 | 2021-10-11 00:00:00.123456789 | 10    |
| 2021-03-11 00:00:00.123456789 | 2021 | 2021-10-11 00:00:00.123456789 | 10    |
| 2021-04-11 00:00:00.123456789 | 2021 | 2021-10-11 00:00:00.123456789 | 10    |
| 2021-05-11 00:00:00.123456789 | 2021 | 2021-10-11 00:00:00.123456789 | 10    |
| 2021-06-11 00:00:00.123456789 | 2021 | 2021-10-11 00:00:00.123456789 | 10    |
| 2021-07-11 00:00:00.123456789 | 2021 | 2021-10-11 00:00:00.123456789 | 10    |
| 2021-08-11 00:00:00.123456789 | 2021 | 2021-10-11 00:00:00.123456789 | 10    |
| 2021-09-11 00:00:00.123456789 | 2021 | 2021-10-11 00:00:00.123456789 | 10    |
| 2021-10-11 00:00:00.123456789 | 2021 | 2021-10-11 00:00:00.123456789 | 10    |
+-------------------------------+------+-------------------------------+-------+

相关函数

EXTRACT函数属于日期函数，更多日期计算、日期转换的相关函数请参见日期函数。

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