如果在定义VARRAY的时候带上NOT NULL限制，那么这个VARRAY的元素就不能为NULL.
如下定义：
CREATE OR REPLACE TYPE integer_varray
AS VARRAY(5) OF INTEGER NOT NULL;
/
然后有一个ＰＬＳＱＬ块如下：
DECLARE
-- Declare and initialize a null set of rows.
varray_integer INTEGER_VARRAY := integer_varray();
BEGIN
-- Loop through all records to print the varray contents.
FOR i IN 1..varray_integer.LIMIT LOOP
-- Initialize row.
varray_integer.EXTEND;
/*没有赋值,如果不赋值是NULL的话，应该编译错误啊，结果是顺利通过编译*/
END LOOP;
-- Print to console how many rows are initialized.
dbms_output.put ('Integer Varray Initialized ');
dbms_output.put_line('['||varray_integer.COUNT||']');
--varray_integer(1):=null;
FOR i IN 1..varray_integer.COUNT LOOP
-- Print the contents.
dbms_output.put ('Integer Varray ['||i||'] ');
dbms_output.put_line('['||varray_integer(i)||']');
if(varray_integer(i) is null) then
/*本来是认为这里应该不执行，结果会打印出来*/
dbms_output.put_line('Integer Varray ['||i||'] '|| 'is null');
end if;
END LOOP;
END;
/
运行结果如下：/*运行也正常，显示元素为NULL，于定义矛盾*/
Integer Varray Initialized [5]
Integer Varray [1] []
Integer Varray [1] is null
Integer Varray [2] []
Integer Varray [2] is null
Integer Varray [3] []
Integer Varray [3] is null
Integer Varray [4] []
Integer Varray [4] is null
Integer Varray [5] []
Integer Varray [5] is null
测试环境为：