Subtracting xs:dateTime Values

Subtracting xs:dateTime Values

The final date/time functions in this chapter involve subtracting xs:dateTime values. We saw earlier that there are various operators that take care of subtraction for the date/time types, but with these functions you can specify if you want the result as an xdt:yearMonthDuration value or an xdt:dayTimeDuration value:

• fn:subtract-dateTimes-yielding-yearMonthDuration returns the difference between two xs:dateTime values as an xdt:yearMonthDuration value.

• fn:subtract-dateTimes-yielding-dayTimeDuration returns the difference between two xs:dateTime values as an xdt:dayTimeDuration value.

The fn:subtract-dateTimes-yielding-yearMonthDuration Function

As you can gather from its name , this function returns an xdt:yearMonthDuration value when you subtract two xs:dateTime values. Here's how you use it:

 fn:subtract-dateTimes-yielding-yearMonthDuration(  $srcval1  as xs:dateTime,  $srcval2  as xs:dateTime) as xdt:yearMonthDuration 

The return value is an xdt:yearMonthDuration value containing the difference between $srcval1 and $srcval2 .

For example, this expression returns an xdt:yearMonthDuration value holding the value 11 months:

 fn:subtract-dateTimes-yielding-yearMonthDuration(xs:dateTime("2004-01-30T19:48:00"),     xs:dateTime("2003-02-28T12:00:00")) 

The fn:subtract-dateTimes-yielding-dayTimeDuration Function

This function returns the difference between two xs:dateTime values as an xdt:dayTimeDuration value:

 fn:subtract-dateTimes-yielding-dayTimeDuration($srcval1 as xs:dateTime,     $srcval2 as xs:dateTime) as xdt:dayTimeDuration 

The return value is an xdt:dayTimeDuration value that contains the difference between $srcval1 and $srcval2 as an xdt:dayTimeDuration value.

For example, this expression returns an xdt:dayTimeDuration value corresponding to 1 day, 3 hours, 22 minutes, and 2 seconds:

 fn:subtract-dateTimes-yielding-dayTimeDuration(xs:dateTime("2004-04-09T04:22:07"),     xs:dateTime("2004-04-08T01:00:05"))