問２
(1)mysql> select salary,name from emloyee
    -> where salary is NULL or salary<=300000;
+--------+----------+
| salary | name     |
+--------+----------+
|   NULL | 山田太郎 |
| 250000 | 佐藤次郎 |
| 250000 | 鈴木花子 |
| 300000 | 高橋良子 |
+--------+----------+
4 rows in set (0.00 sec)

(2)mysql> select birthday,name from emloyee
    -> where not birthday<1990;
+------------+----------+
| birthday   | name     |
+------------+----------+
| 1995-01-01 | 山田太郎 |
| 1990-05-03 | 佐藤次郎 |
| 1990-02-11 | 鈴木花子 |
| 1975-11-03 | 田中三郎 |
| 1985-11-23 | 高橋良子 |
| 1970-05-03 | 鈴木良枝 |
| 1980-05-05 | 鈴木健次 |
+------------+----------+
7 rows in set, 1 warning (0.00 sec)

(3)
mysql> select name,salary from emloyee
    -> where salary>300000 and salary<=400000;
+----------+--------+
| name     | salary |
+----------+--------+
| 田中三郎 | 400000 |
| 鈴木健次 | 350000 |
+----------+--------+

(4)
mysql> select name,salary from emloyee
    -> where salary between 300000 and 399999;
+----------+--------+
| name     | salary |
+----------+--------+
| 高橋良子 | 300000 |
| 鈴木健次 | 350000 |
+----------+--------+

(5)mysql> select name,gender,salary,dep_id from emloyee
    -> where gender='男' or salary>=400000 or dep_id='D001';
+----------+--------+--------+--------+
| name     | gender | salary | dep_id |
+----------+--------+--------+--------+
| 山田太郎 | 男     |   NULL | NULL   |
| 佐藤次郎 | 男     | 250000 | D001   |
| 田中三郎 | 男     | 400000 | D003   |
| 鈴木良枝 | 女     | 450000 | D003   |
| 鈴木健次 | 男     | 350000 | D001   |
+----------+--------+--------+--------+
5 rows in set (0.00 sec)