DATE_SUB - MaxCompute

按照delta幅度增減startdate日期的天數。

注意事項

如果您需要擷取在目前時間基礎上指定變動幅度的日期，請結合GETDATE函數使用。

本命令與DATE_ADD的增減邏輯相反。

命令格式

date date_sub(date|timestamp|string <startdate>, bigint <delta>)

參數說明

startdate：必填。起始日期值。支援DATE、DATETIME或STRING類型。
如果參數為STRING類型，且MaxCompute專案的資料類型版本是1.0，則會隱式轉換為DATE類型後參與運算，且STRING參數格式至少要包含'yyyy-mm-dd'。例如'2019-12-27'。
delta：必填。修改幅度。BIGINT類型。如果delta大於0，則減；delta小於0，則增；delta等於0，不增不減。

傳回值說明

返回DATE類型，格式為yyyy-mm-dd。返回規則如下：

startdate非DATE、DATETIME或STRING類型時，返回報錯。
startdate值為NULL時，返回報錯。
delta值為NULL時，返回NULL。

樣本資料

為便於理解各函數的使用方法，本文為您提供來源資料，基於來源資料提供函數相關樣本。建立表mf_date_fun_t，並添加資料，命令樣本如下。

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);

查詢表mf_date_fun_t中的資料，命令樣本如下：

select * from mf_date_fun_t;
--返回結果。
+------+-------+------------+------------+-------+------------+------------+-------+------------+
| id   | date1 | datetime1  | timestamp1 | date2 | datetime2  | timestamp2 | date3 | date4      |
+------+-------+------------+------------+-------+------------+------------+-------+------------+
| 1    | 2021-11-29 | 2021-11-29 00:01:00 | 2021-01-11 00:00:00.123456789 | 2021-10-29 | 2021-10-29 00:00:00 | 2021-10-11 00:00:00.123456789 | 2021-11-20 | 123456780  |
| 2    | 2021-11-28 | 2021-11-28 00:02:00 | 2021-02-11 00:00:00.123456789 | 2021-10-29 | 2021-10-29 00:00:00 | 2021-10-11 00:00:00.123456789 | 2021-11-21 | 123456781  |
| 3    | 2021-11-27 | 2021-11-27 00:03:00 | 2021-03-11 00:00:00.123456789 | 2021-10-29 | 2021-10-29 00:00:00 | 2021-10-11 00:00:00.123456789 | 2021-11-22 | 123456782  |
| 4    | 2021-11-26 | 2021-11-26 00:04:00 | 2021-04-11 00:00:00.123456789 | 2021-10-29 | 2021-10-29 00:00:00 | 2021-10-11 00:00:00.123456789 | 2021-11-23 | 123456783  |
| 5    | 2021-11-25 | 2021-11-25 00:05:00 | 2021-05-11 00:00:00.123456789 | 2021-10-29 | 2021-10-29 00:00:00 | 2021-10-11 00:00:00.123456789 | 2021-11-24 | 123456784  |
| 6    | 2021-11-24 | 2021-11-24 00:06:00 | 2021-06-11 00:00:00.123456789 | 2021-10-29 | 2021-10-29 00:00:00 | 2021-10-11 00:00:00.123456789 | 2021-11-25 | 123456785  |
| 7    | 2021-11-23 | 2021-11-23 00:07:00 | 2021-07-11 00:00:00.123456789 | 2021-10-29 | 2021-10-29 00:00:00 | 2021-10-11 00:00:00.123456789 | 2021-11-26 | 123456786  |
| 8    | 2021-11-22 | 2021-11-22 00:08:00 | 2021-08-11 00:00:00.123456789 | 2021-10-29 | 2021-10-29 00:00:00 | 2021-10-11 00:00:00.123456789 | 2021-11-27 | 123456787  |
| 9    | 2021-11-21 | 2021-11-21 00:09:00 | 2021-09-11 00:00:00.123456789 | 2021-10-29 | 2021-10-29 00:00:00 | 2021-10-11 00:00:00.123456789 | 2021-11-28 | 123456788  |
| 10   | 2021-11-20 | 2021-11-20 00:10:00 | 2021-10-11 00:00:00.123456789 | 2021-10-29 | 2021-10-29 00:00:00 | 2021-10-11 00:00:00.123456789 | 2021-11-29 | 123456789  |
+------+-------+------------+------------+-------+------------+------------+-------+------------+

使用樣本：待用資料樣本

--開啟2.0新類型。此命令需要與SQL語句一起提交。
set odps.sql.type.system.odps2=true;
--返回2005-02-28。減1天，實際值為上個月的最後1天。
select date_sub(datetime '2005-03-01 00:00:00', 1);
--返回2005-03-01。增1天。
select date_sub(date '2005-02-28', -1);
--返回2005-02-27。減2天。
set odps.sql.type.system.odps2=false; 
select date_sub('2005-03-01 00:00:00', 2);
--假設目前時間為2021-09-10 16:31:44，返回2021-09-09。
select date_sub(getdate(),1);
--返回NULL。
select date_sub('2005-03-01 00:00:00', null);

使用樣本：表資料樣本

基於樣本資料，對date1、datetime1和timestamp1列按照幅度變化天數，命令樣本如下。

--開啟2.0新類型。此命令需要與SQL語句一起提交。
set odps.sql.type.system.odps2=true;
select date1, date_sub(date1,1) as date1_date_sub, datetime1, date_sub(datetime1,-1) as datetime1_date_sub, timestamp1, date_sub(timestamp1,0) as timestamp1_date_sub from mf_date_fun_t;

返回結果如下。

+------------+----------------+---------------------+--------------------+-------------------------------+---------------------+
| date1      | date1_date_sub | datetime1           | datetime1_date_sub | timestamp1                    | timestamp1_date_sub |
+------------+----------------+---------------------+--------------------+-------------------------------+---------------------+
| 2021-11-29 | 2021-11-28     | 2021-11-29 00:01:00 | 2021-11-30         | 2021-01-11 00:00:00.123456789 | 2021-01-11          |
| 2021-11-28 | 2021-11-27     | 2021-11-28 00:02:00 | 2021-11-29         | 2021-02-11 00:00:00.123456789 | 2021-02-11          |
| 2021-11-27 | 2021-11-26     | 2021-11-27 00:03:00 | 2021-11-28         | 2021-03-11 00:00:00.123456789 | 2021-03-11          |
| 2021-11-26 | 2021-11-25     | 2021-11-26 00:04:00 | 2021-11-27         | 2021-04-11 00:00:00.123456789 | 2021-04-11          |
| 2021-11-25 | 2021-11-24     | 2021-11-25 00:05:00 | 2021-11-26         | 2021-05-11 00:00:00.123456789 | 2021-05-11          |
| 2021-11-24 | 2021-11-23     | 2021-11-24 00:06:00 | 2021-11-25         | 2021-06-11 00:00:00.123456789 | 2021-06-11          |
| 2021-11-23 | 2021-11-22     | 2021-11-23 00:07:00 | 2021-11-24         | 2021-07-11 00:00:00.123456789 | 2021-07-11          |
| 2021-11-22 | 2021-11-21     | 2021-11-22 00:08:00 | 2021-11-23         | 2021-08-11 00:00:00.123456789 | 2021-08-11          |
| 2021-11-21 | 2021-11-20     | 2021-11-21 00:09:00 | 2021-11-22         | 2021-09-11 00:00:00.123456789 | 2021-09-11          |
| 2021-11-20 | 2021-11-19     | 2021-11-20 00:10:00 | 2021-11-21         | 2021-10-11 00:00:00.123456789 | 2021-10-11          |
+------------+----------------+---------------------+--------------------+-------------------------------+---------------------+

MaxCompute：DATE_SUB