if — If the boolean value is true then calculates one
expression, otherwise calculates another expression.
test boolean ,
then_branch any ,
else_branch any );
This function calculates the value of test argument. If the value is true,
the function calculates the then_branch expression and returns
its value. If the value is false, the function calculates the
else_branch expression and
returns its value.
Note that unlike other programming languages, else_branch is required argument, not
This function is used in the implementation of "IF" control
operator in XQUERY, so you will probably use that operator in
XQUERY expressions, not the function. This function may be useful
in XPATH expressions and in XSLT stylesheets. It is not a part of
library of standard XQUERY 1.0 functions.
Boolean value used to choose an expression to execute
Expression which is calculated if test argument is true
Expression which is calculated if test argument is false
These two expressions are equivalent, but first may be used in
any XPATH while second is written in XQUERY syntax:
if (2 * 2 = 4, 'I think so', 'Unbelievable!')
IF 2 * 2 = 4 THEN 'I think so' ELSE 'Unbelievable!'