mysql> select name,salary from new_employee where salary<300000 or salary is null;
+-----------+--------+
| name      | salary |
+-----------+--------+
| 山田太郎  |   NULL |
| 佐藤次郎  | 250000 |
| 鈴木花子  | 227500 |
| 田中三郎  | 250000 |
| 田中良子  | 273000 |
| 山本景子  | 227500 |
| 渡辺五郎  | 260000 |
+-----------+--------+
7 rows in set (0.00 sec)


mysql> select name,birthday from employee
    -> where not birthday>='1990-01-01' and birthday<='1999-12-31';
+----------+------------+
| name     | birthday   |
+----------+------------+
| 田中三郎 | 1975-11-03 |
| 高橋良子 | 1985-11-23 |
| 鈴木良枝 | 1970-05-03 |
| 佐藤健次 | 1980-05-05 |
+----------+------------+
4 rows in set (0.04 sec)



mysql> select name,salary from new_employee where salary>300000 and salary<400000;
+-----------+--------+
| name      | salary |
+-----------+--------+
| 佐藤健次  | 350000 |
+-----------+--------+
1 row in set (0.00 sec)




mysql> select name,salary from new_employee where salary between  300000 and 399999;
+-----------+--------+
| name      | salary |
+-----------+--------+
| 佐藤健次  | 350000 |
+-----------+--------+
1 row in set (0.04 sec)






mysql> select name,salary,dep_id from new_employee where gender='男' or salary>=300000 or dep_id='D001';
+-----------+--------+--------+
| name      | salary | dep_id |
+-----------+--------+--------+
| 山田太郎  |   NULL | NULL   |
| 佐藤次郎  | 250000 | D001   |
| 田中三郎  | 250000 | D003   |
| 鈴木良枝  | 409500 | D003   |
| 佐藤健次  | 350000 | D001   |
| 渡辺五郎  | 260000 | D004   |
+-----------+--------+--------+
6 rows in set (0.00 sec)