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Calculates the date that results from adding a specified number of months to a date. This function is an extension function for MaxCompute V2.0.

Command format

string add_months(date|datetime|timestamp|string <startdate>, int <num_months>)

Parameters

startdate: Required. A value of the DATE, DATETIME, TIMESTAMP, or STRING type. The supported formats are yyyy-mm-dd, yyyy-mm-dd hh:mi:ss, or yyyy-mm-dd hh:mi:ss.ff3. If you specify a value of the STRING type, it must contain at least the yyyy-mm-dd part and no other characters.
num_months: Required. An INT value.

Return value

The function returns a STRING value in the yyyy-mm-dd format. This value represents the date that is num_months after startdate. The function follows these rules:

If startdate is not a valid DATE, DATETIME, TIMESTAMP, or STRING type, or if its format is incorrect, the function returns NULL.
If the value of startdate is NULL, an error is reported.
If the value of num_months is NULL, the function returns NULL.

Sample data

This topic provides sample data and examples to help you understand this function. You can create the `mf_date_fun_t` table and insert data into it by running the following command.

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);

Query the data in the `mf_date_fun_t` table:

select * from mf_date_fun_t;
-- The following result is returned.
+------+-------+------------+------------+-------+------------+------------+-------+------------+
| 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  |
+------+-------+------------+------------+-------+------------+------------+-------+------------+

Examples with static data

-- Returns 2017-05-14.
select add_months('2017-02-14',3);
-- Returns 2017-05-14.
select add_months('2017-2-14',3);
-- Returns 2017-05-14.
select add_months('2017-02-14 21:30:00',3);
-- Returns NULL.
select add_months('20170214',3);
-- Returns NULL.
select add_months('2017-02-14 21:30:00',null);

Examples with table data

The following example command converts the dates in the date1, datetime1, timestamp1, and date3 columns from the sample data to integer UNIX timestamps.

-- Enable MaxCompute V2.0 data types. This command must be submitted with the SQL statement.
set odps.sql.type.system.odps2=true;
select date1, add_months(date1,1) as date1_add_months, datetime1, add_months(datetime1, 2) as datetime1_add_months, timestamp1, add_months(timestamp1,3) as timestamp1_add_months, date3, add_months(date3,4) as date3_add_months from mf_date_fun_t;

The following result is returned.

+------------+------------------+---------------------+----------------------+-------------------------------+-----------------------+------------+------------------+
| date1      | date1_add_months | datetime1           | datetime1_add_months | timestamp1                    | timestamp1_add_months | date3      | date3_add_months |
+------------+------------------+---------------------+----------------------+-------------------------------+-----------------------+------------+------------------+
| 2021-11-29 | 2021-12-29       | 2021-11-29 00:01:00 | 2022-01-29           | 2021-01-11 00:00:00.123456789 | 2021-04-11            | 2021-11-20 | 2022-03-20       |
| 2021-11-28 | 2021-12-28       | 2021-11-28 00:02:00 | 2022-01-28           | 2021-02-11 00:00:00.123456789 | 2021-05-11            | 2021-11-21 | 2022-03-21       |
| 2021-11-27 | 2021-12-27       | 2021-11-27 00:03:00 | 2022-01-27           | 2021-03-11 00:00:00.123456789 | 2021-06-11            | 2021-11-22 | 2022-03-22       |
| 2021-11-26 | 2021-12-26       | 2021-11-26 00:04:00 | 2022-01-26           | 2021-04-11 00:00:00.123456789 | 2021-07-11            | 2021-11-23 | 2022-03-23       |
| 2021-11-25 | 2021-12-25       | 2021-11-25 00:05:00 | 2022-01-25           | 2021-05-11 00:00:00.123456789 | 2021-08-11            | 2021-11-24 | 2022-03-24       |
| 2021-11-24 | 2021-12-24       | 2021-11-24 00:06:00 | 2022-01-24           | 2021-06-11 00:00:00.123456789 | 2021-09-11            | 2021-11-25 | 2022-03-25       |
| 2021-11-23 | 2021-12-23       | 2021-11-23 00:07:00 | 2022-01-23           | 2021-07-11 00:00:00.123456789 | 2021-10-11            | 2021-11-26 | 2022-03-26       |
| 2021-11-22 | 2021-12-22       | 2021-11-22 00:08:00 | 2022-01-22           | 2021-08-11 00:00:00.123456789 | 2021-11-11            | 2021-11-27 | 2022-03-27       |
| 2021-11-21 | 2021-12-21       | 2021-11-21 00:09:00 | 2022-01-21           | 2021-09-11 00:00:00.123456789 | 2021-12-11            | 2021-11-28 | 2022-03-28       |
| 2021-11-20 | 2021-12-20       | 2021-11-20 00:10:00 | 2022-01-20           | 2021-10-11 00:00:00.123456789 | 2022-01-11            | 2021-11-29 | 2022-03-29       |
+------------+------------------+---------------------+----------------------+-------------------------------+-----------------------+------------+------------------+

Related functions

ADD_MONTHS is a date function. For more information about functions for date calculations and conversions, see Date functions.