问题
I'm trying to delete all tables from a database except one, and I end up having the following error:
Cannot delete or update a parent row: a foreign key constraint fails
Of course I could trial and error to see what those key constraints are and eventually delete all tables but I'd like to know if there is a fast way to force drop all tables (as I'll be able to re-insert those I don't want deleted).
Google aimed me at some site that suggested the following method:
mysql> SET foreign_key_checks = 0;
mysql> drop table ...
mysql> SET foreign_key_checks = 1;
Short answer is it didn't really do the trick since I ended up receiving the same error while I was able to delete some more tables. I've seen on Stack Overflow ways to get all foreign keys linked to a certain table but that's way too time consuming unless I script it all (which is doable in the case there is no other option)
Database is 4.1 so I can't use DROP DATABASE
Ideas?
回答1:
Since you are not interested in keeping any data, drop the entire database and create a new one.
回答2:
This might be useful to someone ending up here from a search. Make sure you're trying to drop a table and not a view.
SET foreign_key_checks = 0; -- Drop tables drop table ... -- Drop views drop view ... SET foreign_key_checks = 1;
SET foreign_key_checks = 0 is to set foreign key checks to off and then SET foreign_key_checks = 1 is to set foreign key checks back on. While the checks are off the tables can be dropped, the checks are then turned back on to keep the integrity of the table structure.
回答3:
If you are using phpmyadmin then this feature is already there.
- Select the tables you want to drop
- From the dropdown at the bottom of tables list, select drop
- A new page will be opened having checkbox at the bottom saying "Foreign key check", uncheck it.
- Confirm the deletion by accepting "yes".
回答4:
You can use the following steps, its worked for me to drop table with constraint,solution already explained in the above comment, i just added screen shot for that -
回答5:
Drop database exist in all versions of MySQL. But if you want to keep the table structure, here is an idea
mysqldump --no-data --add-drop-database --add-drop-table -hHOSTNAME -uUSERNAME -p > dump.sql
This is a program, not a mysql command
Then, log into mysql and
source dump.sql;
回答6:
Simple solution to drop all the table at once from terminal.
This involved few steps inside your mysql shell (not a one step solution though), this worked me and saved my day.
Worked for Server version: 5.6.38 MySQL Community Server (GPL)
Steps I followed:
1. generate drop query using concat and group_concat.
2. use database
3. turn off / disable foreign key constraint check (SET FOREIGN_KEY_CHECKS = 0;),
4. copy the query generated from step 1
5. re enable foreign key constraint check (SET FOREIGN_KEY_CHECKS = 1;)
6. run show table
MySQL shell
$ mysql -u root -p
Enter password: ****** (your mysql root password)
mysql> SYSTEM CLEAR;
mysql> SELECT CONCAT('DROP TABLE IF EXISTS `', GROUP_CONCAT(table_name SEPARATOR '`, `'), '`;') AS dropquery FROM information_schema.tables WHERE table_schema = 'emall_duplicate';
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| dropquery |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| DROP TABLE IF EXISTS `admin`, `app`, `app_meta_settings`, `commission`, `commission_history`, `coupon`, `email_templates`, `infopages`, `invoice`, `m_pc_xref`, `member`, `merchant`, `message_templates`, `mnotification`, `mshipping_address`, `notification`, `order`, `orderdetail`, `pattributes`, `pbrand`, `pcategory`, `permissions`, `pfeatures`, `pimage`, `preport`, `product`, `product_review`, `pspecification`, `ptechnical_specification`, `pwishlist`, `role_perms`, `roles`, `settings`, `test`, `testanother`, `user_perms`, `user_roles`, `users`, `wishlist`; |
+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
mysql> USE emall_duplicate;
Database changed
mysql> SET FOREIGN_KEY_CHECKS = 0; Query OK, 0 rows affected (0.00 sec)
// copy and paste generated query from step 1
mysql> DROP TABLE IF EXISTS `admin`, `app`, `app_meta_settings`, `commission`, `commission_history`, `coupon`, `email_templates`, `infopages`, `invoice`, `m_pc_xref`, `member`, `merchant`, `message_templates`, `mnotification`, `mshipping_address`, `notification`, `order`, `orderdetail`, `pattributes`, `pbrand`, `pcategory`, `permissions`, `pfeatures`, `pimage`, `preport`, `product`, `product_review`, `pspecification`, `ptechnical_specification`, `pwishlist`, `role_perms`, `roles`, `settings`, `test`, `testanother`, `user_perms`, `user_roles`, `users`, `wishlist`;
Query OK, 0 rows affected (0.18 sec)
mysql> SET FOREIGN_KEY_CHECKS = 1;
Query OK, 0 rows affected (0.00 sec)
mysql> SHOW tables;
Empty set (0.01 sec)
mysql>
来源：https://stackoverflow.com/questions/2300396/force-drop-mysql-bypassing-foreign-key-constraint