You can cast an element from one data type to another using a built-in XQuery cast function when:
Type promotion does not occur.
The data comes from a variable or an other source that is not a constant
A built-in function that performs the cast you want is available in the Design Palette.
To cast using a built-in XQuery function:
Click the Update Map tab.
Click the disabled element in an update block on the left.
In the expression editor, you see an expression that uses fn-bea:value() to map from the return type on the right, for example:
fn-bea:value($CUSTOMER/CUSTOMER_SINCE)
This expression represents a dateTime value coming from the return type.
Open the Design Palette
Window > Show View > Design Palette
Expand XQuery Functions, then a category (for example, Duration, Date, and Time Functions).
Drag the function you want to the expression editor (for example, fn-bea:date-from-dateTime), leaving the existing expression there.
If feasible, use the existing expression as an argument to the function, for example: