Collection functions

The following table describes the supported collection functions.

Function	Description
CARDINALITY	Returns the number of elements in a nested table as a NUMBER. If the nested table is empty or null, returns NULL.
COLLECT	Creates a nested table from a column of any type as an aggregate function. For accurate results, use within a CAST function.
POWERMULTISET	Returns a nested table of nested tables containing all nonempty subsets (submultisets) of the input nested table.
POWERMULTISET_BY_CARDINALITY	Returns a nested table of nested tables containing all nonempty subsets (submultisets) of the input nested table with the specified cardinality.
SET	Converts a nested table into a set by removing duplicates. Returns a nested table of the same type as the input, with distinct elements only.