The operations of addition and subtraction are allowed as follows, where integer values represent the number of days:
| Argument 1 | Operation | Argument 2 | Result |
|---|---|---|---|
| DATE | + | INTEGER | DATE |
| DATE | - | INTEGER | DATE |
| INTEGER | + | DATE | DATE |
| DATE | - | DATE | INTEGER |
Adding 90 days, for example, is not identical to adding 3 months, because of the varying number of days in months.
Also, adding multiples of 365 days is not identical to adding years because of leap years.
Note that scalar operations on Teradata DATE expressions are performed using ANSI SQL:2011 data types, so an expression of the type date_expression - numeric_expression is treated as if the numeric_expression component were typed as INTERVAL DAY.
ANSI SQL:2011 DateTime and Interval values have their own set of scalar operations and with the exception of the scalar operations defined here for DATE, do not support the implicit conversions to resolve expressions of mixed data types.