This type of duration represents a specific unit of time as expressed by a number followed by one of the following keywords:
| YEAR | YEARS |
| MONTH | MONTHS |
| DAY | DAYS |
| HOUR | HOURS |
| MINUTE | MINUTES |
| SECOND | SECONDS |
| MICROSECOND | MICROSECONDS |
The value of the labeled duration can be the result of an expression. It is treated as a DECIMAL(15,0) number. To use a labeled duration in a date-time computation, the other arithmetic operator must be a DATE, TIME or TIMESTAMP data field. Consider the following expression examples where ORDERDATE is a date field being added to two labeled durations (2 MONTHS and 14 DAYS).
ORDERDATE + 2 MONTHS + 14 DAYS This is a valid entry because the expression is resolved from left to right, with ORDERDATE + 2 MONTHS yielding a DATE. The labeled duration 14 DAYS is then added to the new DATE. This expression is the same as (ORDERDATE + 2 MONTHS) + 14 DAYS. ORDERDATE + (2 MONTHS + 14 DAYS) This is not a valid entry because a labeled duration cannot be added to another labeled duration (2 MONTHS cannot be added to 14 DAYS).