Changes

The [https://en.wikipedia.org/wiki/%3F: ternary if] operator provides a short syntax for conditions. It is also called '''conditional operator''' or '''ternary operator'''. In most languages , the syntax is <code>a ? b : c</code>. As <code>?</code> and <code>:</code> have already been taken in XQuery, the syntax of Perl 6 syntax is used:

The Elvis operator returns is also available in other languages. It is sometimes called [https://en.wikipedia.org/wiki/Null_coalescing_operator null-coalescing operator]. In XQuery, the value of the first operand will be returned if it’s it is a non-empty sequence. Otherwise, or the value of the second operand otherwise:will be returned.

let $number := 123return ( (: if/then/else :) if (exists($number)) then $number else 0, (: elvis operator :) $number ?: 0)

It The behavior of the operator is equivalent to the {{Function|Utility|util:or}} function.

In the XQuery standard3.1, both branches of the <code>if</code> expression need to be specified. As in In many cases, only one branch is required, so the <code>else</code> branch is was made optional in BaseX. If the second branch is omitted, an empty sequence is will be returned if the effective boolean value of the test expression is false. Some examples:

if ($a) then if($b) then '$a and $b yield is true' else 'only $b is true'

As in other languagesIn general, it is recommendable to use if you have multiple or nested if expressions, additional parentheses to make a query better readablecan improve the readibility of your code:

if($b) then '$a and $b yield is true' else 'only $b is true'

* <code>basex</code> is used as the default serialization method: nodes are serialized as XML, atomic values are serialized as string, and items of binary type are output in their native byte representation. Function items (including maps and arrays) are output just like with the [[XQuery 3.1#Adaptive Serialization|adaptive]] method.* With {{Code|csv}} allows , you to can output XML nodes as CSV data (see the [[CSV Module]] for more details).* With {{Code|json}}, items are output as JSON as described in the [https://www.w3.org/TR/xslt-xquery-serialization-31/#json-output official specification]. If the root node is of type {{Code|element(json)}}, items are serialized as described for the {{Code|direct}} format in the [[JSON Module]].