The ARRAY constructor returns an array specified by a list
of expressions or a fullselect.

>>-ARRAY--[--+------------------------+--]---------------------><
+-fullselect-------------+
| .-,------------------. |
| V | |
'---element-expression-+-'
- fullselect
- A fullselect that returns a single column. The values returned
by the fullselect are the elements of the array. The cardinality of
the array is equal to the number of rows returned by the fullselect.
An ORDER BY clause in the fullselect can be used to specify the order
among the elements of the array; otherwise, the order is undefined.
- element-expression
- An expression defining the value of an element within the array.
The cardinality of the array is equal to the number of element expressions.
The first element-expression is assigned to the array element
with subindex 1. The second element-expression is assigned
to the array element with subindex 2, and so on. All element expressions
must have compatible data types.
If there is no expression within the brackets,
the result is an empty array. The cardinality of an empty array is
0.