Oracle--NOT EXISTS 与 NOT IN 的区别

11g之后的oracle版本。
一致的状况：存在性判断的话，不影响结果。

CREATE TABLE students (
ID  NUMBER ,
NAME VARCHAR2(20)
)
CREATE TABLE lesson (
ID  NUMBER ,
kc VARCHAR2(20)
)
TRUNCATE TABLE students
INSERT INTO students VALUES (1,'ws');
INSERT INTO students VALUES (2,'gw');
INSERT INTO students VALUES (4,'jr');
INSERT INTO lesson VALUES (1,'sx');
INSERT INTO lesson VALUES (2,NULL);
INSERT INTO lesson VALUES (3,NULL);
INSERT INTO lesson VALUES (NULL,NULL);
SELECT * FROM students;
SELECT * FROM lesson;
SELECT * FROM students s
WHERE NOT  EXISTS (
SELECT 1 FROM lesson l WHERE s.id = l.id
)
SELECT * FROM students s WHERE s.id NOT IN
(
       SELECT 1 FROM lesson WHERE 1=23
)

不一致的情况：
比对字段内的值的情况，如果有null会影响判断。

SELECT * FROM students s WHERE s.id NOT IN
(
       SELECT id FROM lesson 
)