XQuery

xs:duration

The primitive type xs:duration represents a duration of time. It allows you to specify a number of years (Y), months (M), days (D), hours (H), minutes (M), and seconds (S). The lexical representation of xs:duration is PnYnMnDTnHnMnS, where an uppercase P starts the expression, n indicates the quantity of each component, and an uppercase letter T separates the day and time components. For example, the value P3YT5H represents a period of three years and five hours.

The following rules apply to xs:duration values:

• A minus sign may appear at the beginning of the value (before the P) to indicate a negative duration.

• You can omit components whose quantity is zero, but at least one component is required.

• If no time components (hours, minutes, seconds) are specified, the T cannot appear.

• The numbers must be integers, except for the number of seconds, which can include a decimal point. XQuery implementations are required to support up to three fractional digits in the number of seconds, but may support more.

• If a decimal point appears in the number of seconds, there must be at least one digit after the decimal point.

Table B-9 lists some values of the xs:duration type. For more information on working with durations, see Chapter 19.

Table B-9. Values of the xs:duration type

Values	Explanation
Valid
P3Y5M8DT9H25M20S	3 years, 5 months, 8 days, 9 hours, 25 minutes, 20 seconds
P2DT3H	2 day, 3 hours
P25M	25 months (the number of months may be more than 12)
PT25M	25 minutes ...