Functions and Operators

EdgeDB provides a number of functions for the standard data types. Custom functions can be created using function declarations or CREATE FUNCTION DDL statements.

The syntax for a function call is as follows:

function_name "(" [argument [, argument, ...]] ")"

Here function_name is a possibly qualified name of a function, and argument is an expression optionally prefixed with an argument name and the assignment operator (:=).

For example, the following computes the length of a string 'foo':

db> 

SELECT len('foo');

{3}

Many built-in and user-defined functions operate on elements, so they are element-wise operations. This implies that if any of the input sets are empty, the result of applying an element function is also empty.

Aggregate functions are set functions mapping arbitrary sets onto singletons. Examples of aggregate functions include built-ins such as count() and array_agg().

# count maps a set to an integer, specifically it returns the
# number of elements in a set
SELECT count(example::Issue);

# array_agg maps a set to an array of the same type, specifically
# it returns the array made from all of the set elements (which
# can also be ordered)
WITH MODULE example
SELECT array_agg(Issue ORDER BY Issue.number);