select * from emp where comm not in (null,200);
Empty set
select empno,ename,comm from emp where comm not in (200) and comm is not null;
+-------+--------+----------+
| empno | ename | comm |
+-------+--------+----------+
| 6 | 彭和尚 | 20000.00 |
| 7 | 张中 | 10000.00 |
| 8 | 说不得 | 15000.00 |
| 9 | 冷谦 | 10000.00 |
| 10 | 周巅 | 30000.00 |
+-------+--------+----------+
5 rows in set (0.26 sec)
select empno,ename,comm from emp where comm in (null,200);
+-------+--------+--------+
| empno | ename | comm |
+-------+--------+--------+
| 1 | 张无忌 | 200.00 |
+-------+--------+--------+
1 row in set (0.08 sec)
select empno,ename,comm from emp where comm in (200) or comm is null;
+-------+----------+--------+
| empno | ename | comm |
+-------+----------+--------+
| 1 | 张无忌 | 200.00 |
| 2 | 紫衫龙王 | NULL |
| 3 | 白眉鹰王 | NULL |
| 4 | 金毛狮王 | NULL |
| 5 | 青翼蝙王 | NULL |
| 11 | 殷野王 | NULL |
| 12 | 殷素素 | NULL |
| 13 | 小昭 | NULL |
| 666 | NULL | NULL |
+-------+----------+--------+
9 rows in set (0.29 sec)
select empno,ename,comm from emp where comm != 200;
+-------+--------+----------+
| empno | ename | comm |
+-------+--------+----------+
| 6 | 彭和尚 | 20000.00 |
| 7 | 张中 | 10000.00 |
| 8 | 说不得 | 15000.00 |
| 9 | 冷谦 | 10000.00 |
| 10 | 周巅 | 30000.00 |
+-------+--------+----------+
5 rows in set (0.28 sec)