-- https://docs.oracle.com/en/database/oracle/oracle-database/23/lnpls/plsql-collections-and-records.html
DECLARE  
  TYPE Foursome IS VARRAY(4) OF VARCHAR2(15);  -- VARRAY type
  team Foursome;                               -- varray variable

  TYPE Roster IS TABLE OF VARCHAR2(15);        -- nested table type
  names Roster := Roster('Adams', 'Patel');    -- nested table variable

BEGIN
  IF team IS NULL THEN
    DBMS_OUTPUT.PUT_LINE('team IS NULL');
  ELSE
    DBMS_OUTPUT.PUT_LINE('team IS NOT NULL');
  END IF;

  IF names IS NOT NULL THEN
    DBMS_OUTPUT.PUT_LINE('names IS NOT NULL');
  ELSE
    DBMS_OUTPUT.PUT_LINE('names IS NULL');
  END IF;
END;
/