我有两个表名为
1。 tbl_testquestion（qu_id primary）
+-------+----------+--------+
| qu_id | question | status |
+-------+----------+--------+
| 1 | who | 1 |
+-------+----------+--------+
| 2 | why | 1 |
+-------+----------+--------+
| 3 | what | 1 |
+-------+----------+--------+
2。 tbl_testanswer（id_answer primary）
（ qu_id来自tbl_testquestion，该表是该表的主要内容）
+-----------+-------+--------+----------------+--------+
| id_answer | qu_id | answer | correct_answer | status |
+-----------+-------+--------+----------------+--------+
| 1 | 1 | me | 1 | 1 |
+-----------+-------+--------+----------------+--------+
| 2 | 1 | you | 0 | 1 |
+-----------+-------+--------+----------------+--------+
| 3 | 1 | they | 0 | 1 |
+-----------+-------+--------+----------------+--------+
| 4 | 1 | us | 0 | 1 |
+-----------+-------+--------+----------------+--------+
| 5 | 2 | mark | 0 | 1 |
+-----------+-------+--------+----------------+--------+
| 6 | 2 | chen | 0 | 1 |
+-----------+-------+--------+----------------+--------+
| 7 | 2 | ben | 1 | 1 |
+-----------+-------+--------+----------------+--------+
| 8 | 2 | kun | 0 | 1 |
+-----------+-------+--------+----------------+--------+
因此，当我尝试删除表tbl_testquestion中的任何记录时，应删除所有记录，即 tbl_testanswer
那我怎么能添加外键或其他一些..？