After you declare a collection variable, you declare an
element variable to hold individual elements of the collection. The
data type of the element variable must match the data type of the
collection elements.
For example, to hold an element of the
SET in the primes column, use an element variable declaration
such as the one that the following figure shows. Figure 1: An element variable declaration.
DEFINE p INTEGER;
To declare a variable that holds an element of the twin_primes column,
which holds a nested collection, use a variable declaration such as
the one that the following figure shows.Figure 2: A variable declaration.
DEFINE s SET( INTEGER NOT NULL );
The variable s holds a SET of integers.
Each SET is an element of the LIST stored in twin_primes.