Function Calls
Function calls are another building block of queries. A typical function call might look like:
substring($prodName, 1, 5)
where the name of the function is substring and there are three arguments, separated by commas and surrounded by parentheses. The first argument is a variable reference, whereas the other two are numeric literals.
The XQuery language has over 100 built-in functions, detailed in Appendix A. Chapter 8 explains the details of how to read function signatures and call them. It also explains how to define your own functions.
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