Hi,
In general, the function [ADDMONTH](https://community.denodo.com/docs/html/browse/8.0/en/vdp/vql/functions/datetime_functions/datetime_functions#addmonth) has two parameters where the first parameter specifies the column name (which has the Datetime expression) and the second parameter is an integer to be incremented. Also, the function [ADDDAY](https://community.denodo.com/docs/html/browse/8.0/en/vdp/vql/functions/datetime_functions/datetime_functions#addday) has two parameters, one for mentioning the column_name (which has the Datetime expression) and the other for the integer to be incremented. In both the functions, the integer could either be a positive or a negative value.
Please find below the syntax for the functions to work as expected:
```
SELECT ADDMONTH(ADDMONTH(<column_name>, -12),(EXTRACT(MONTH FROM ADDDAY(<column_name> , -12 )))) from <view_name>;
```
For further information, please refer to the [DATATIME FUNCTIONS](https://community.denodo.com/docs/html/browse/8.0/en/vdp/vql/functions/datetime_functions/datetime_functions) document below the Virtual DataPort VQL Guide section.
If you still need further assistance and if you are a valid support user, you can raise a [Support Case](https://support.denodo.com/cases/add), for further assistance from the Support Team.
Hope this helps!
