Learn XQUERY with Real Code Examples

declare variable $count := 0;
declare variable $isDark := false;

declare function local:updateUI() {
    concat('Counter: ', $count, '
', 'Theme: ', if ($isDark) then 'Dark' else 'Light')
};

declare function local:increment() {
    declare variable $count := $count + 1;
    local:updateUI()
};

declare function local:decrement() {
    declare variable $count := $count - 1;
    local:updateUI()
};

declare function local:reset() {
    declare variable $count := 0;
    local:updateUI()
};

declare function local:toggleTheme() {
    declare variable $isDark := not($isDark);
    local:updateUI()
};

(: Simulate actions :)
local:updateUI();
local:increment();
local:increment();
local:toggleTheme();
local:decrement();
local:reset();

Demonstrates a simple counter with theme toggling using XQuery variables and functional expressions.

declare function local:fib($n) {
  if ($n = 0) then 0
  else if ($n = 1) then 1
  else local:fib($n - 1) + local:fib($n - 2)
};
for $i in 0 to 9 return local:fib($i)

Generates first 10 Fibonacci numbers using XQuery recursion.

declare function local:fact($n) {
  if ($n = 0) then 1 else $n * local:fact($n - 1)
};
local:fact(5)

Calculates factorial of a number using recursion.

declare function local:isPrime($n) {
  $n > 1 and every $i in 2 to $n - 1 satisfies ($n mod $i != 0)
};
local:isPrime(13)

Checks if a number is prime using XQuery sequence and every operator.

sum((1,2,3,4,5))

Calculates sum of a sequence of numbers.

string-join(reverse(string-to-codepoints('HELLO'))!codepoints-to-string,'')

Reverses a string using XQuery string functions.

for $i in 1 to 10 return 5 * $i

Generates multiplication table for a number.

let $c := 25 return $c * 9 div 5 + 32

Converts Celsius to Fahrenheit.

let $temp := 80 let $thresh := 75 return if ($temp > $thresh) then 'Alarm: Temp Too High!' else 'Temp Normal'

Simulates an alarm if threshold exceeded.

declare variable $steps := 10;
declare variable $pos := 0;
for $i in 1 to $steps return ($pos := $pos + (if (fn:random-number() < 0.5) then -1 else 1), $pos)

Simulates a 1D random walk using XQuery random numbers.