条件：p（父表）没有on delete cascade c（子表）
mysql> delete a,b from p a,c b where a.id=b.id;
error 1451 (23000): cannot delete or update a parent row: a foreign key constraint fails (`hhl`.`c`, constraint `fk_p_id` foreign key (`id`) references `p` (`id`))
mysql> show profiles ;
+----------+------------+------------------------------------------+
| query_id | duration | query |
+----------+------------+------------------------------------------+
| 1 | 0.00875600 | delete a,b from p a,c b where a.id=b.id |
| 2 | 0.01294200 | delete a,b from p a,c b where a.id=b.id |
+----------+------------+------------------------------------------+
mysql> show profile for query 2 ;
+--------------------------+----------+
| status | duration |
+--------------------------+----------+
| starting | 0.000314 |
| checking permissions | 0.000026 |
| checking permissions | 0.000014 |
| checking permissions | 0.000009 |
| checking permissions | 0.000010 |
| init | 0.000033 |
| opening tables | 0.000082 |
| system lock | 0.000047 |
| init | 0.000050 |
| deleting from main table | 0.000016 |
| optimizing | 0.000019 |
| statistics | 0.000056 |
| preparing | 0.000042 |
| executing | 0.000054 |
| sending data | 0.005026 |
| end | 0.000050 |
| query end | 0.003456 |
| closing tables | 0.000143 |
| freeing items | 0.003430 |
| logging slow query | 0.000047 |
| cleaning up | 0.000021 |
+--------------------------+----------+
21 rows in set (0.00 sec)
看出上面没有删除子表的操作。
mysql> delete a,b from c a,p b where a.id=b.id;
query ok, 6 rows affected (0.04 sec)
from 后面 子表在前，，删除成功！！
mysql> show profile for query 3 ;
+--------------------------------+----------+
| status | duration |
+--------------------------------+----------+
| starting | 0.000307 |
| checking permissions | 0.000019 |
| checking permissions | 0.000017 |
| checking permissions | 0.000009 |
| checking permissions | 0.000010 |
| init | 0.000021 |
| opening tables | 0.000091 |
| system lock | 0.000036 |
| init | 0.000047 |
| deleting from main table | 0.000016 |
| optimizing | 0.000125 |
| statistics | 0.000084 |
| preparing | 0.000042 |
| executing | 0.000013 |
| sending data | 0.000572 |
| deleting from reference tables | 0.000103 |
| end | 0.000015 |
| waiting for query cache lock | 0.000009 |
| end | 0.000010 |
| waiting for query cache lock | 0.000008 |
| end | 0.000160 |
| end | 0.000022 |
| query end | 0.030033 |
| closing tables | 0.000081 |
| freeing items | 0.001465 |
| logging slow query | 0.000052 |
| cleaning up | 0.000011 |
+--------------------------------+----------+
27 rows in set (0.00 sec)
另一种方式： 先删除最外层的子表，一层一层向里删除，最后删除父表。