Use of xquey function library

Question

i have made an xquery function library which incorporates the add_month function of sql.
add_months($date as xs:dateTime,$value as xs:int) as xs:dateTime?
But while using this function in a let clause in xquery:
let $nextMonth:= ns1:add_months(fn:current-dateTime(),xs:int("1")) i am geting this error;
add_months": unbound external function. Improper use of the user-defined SQL function .

Answer 1

It's "improper" as none of the arguments come from that database, therefore ALDSP will not push it to the database.
This computation can be done in XQuery - what you want to do is to add a YearMonth style 'duration' to the date.
If you go to w3.org, click on Xml Query, click on the 'Functions and Operators' link, then look for in section 10.8.4. Notice this is an 'op' - an operator. It is not a function and you cannot call it directly. Notice the last line in the description - it says it 'backs up the + operator' - so that's how you use it - by using the + operator.
So -
A YearMonth duration of 0 years 1 month is
xs:yearMonthDuration("P0Y1M")
so what you want is :
fn:current-dateTime() + xs:yearMonthDuration("P0Y1M")
If you had a genuine need to call a database function with arguments that did not come from that database, you could do so by creating a New -> Physical Data Service -> Relational -> SQL Statement.