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Foreign keys issue when swapping MySQL tables by renaming

When you swap MySQL tables by renaming,  you need to manually update all the affected foreign keys.

Use Sakila as example:

mysql> SELECT TABLE_NAME, COLUMN_NAME, CONSTRAINT_NAME, REFERENCED_TABLE_NAME, REFERENCED_COLUMN_NAME FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE

WHERE REFERENCED_TABLE_NAME = 'address' and TABLE_SCHEMA = 'sakila';

+------------+-------------+---------------------+-----------------------+------------------------+

| TABLE_NAME | COLUMN_NAME | CONSTRAINT_NAME | REFERENCED_TABLE_NAME | REFERENCED_COLUMN_NAME |

+------------+-------------+---------------------+-----------------------+------------------------+

| customer | address_id | fk_customer_address | address | address_id |

| staff | address_id | fk_staff_address | address | address_id |

| store | address_id | fk_store_address | address | address_id |

+------------+-------------+---------------------+-----------------------+------------------------+

3 rows in set (0.01 sec)


mysql> insert into addr select * from address limit 8;

Query OK, 8 rows affected (0.00 sec)

Records: 8 Duplicates: 0 Warnings: 0


mysql> RENAME TABLE address TO tmp_table,

-> addr TO address,

-> tmp_table TO addr;

Query OK, 0 rows affected (0.02 sec)


mysql> SELECT TABLE_NAME, COLUMN_NAME, CONSTRAINT_NAME, REFERENCED_TABLE_NAME, REFERENCED_COLUMN_NAME FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE

WHERE REFERENCED_TABLE_NAME = 'address' and TABLE_SCHEMA = 'sakila';

Empty set (0.00 sec)


mysql> SELECT TABLE_NAME, COLUMN_NAME, CONSTRAINT_NAME, REFERENCED_TABLE_NAME, REFERENCED_COLUMN_NAME FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE

WHERE REFERENCED_TABLE_NAME = 'addr' and TABLE_SCHEMA = 'sakila';

+------------+-------------+---------------------+-----------------------+------------------------+

| TABLE_NAME | COLUMN_NAME | CONSTRAINT_NAME | REFERENCED_TABLE_NAME | REFERENCED_COLUMN_NAME |

+------------+-------------+---------------------+-----------------------+------------------------+

| customer | address_id | fk_customer_address | addr | address_id |

| staff | address_id | fk_staff_address | addr | address_id |

| store | address_id | fk_store_address | addr | address_id |

+------------+-------------+---------------------+-----------------------+------------------------+

3 rows in set (0.00 sec)


mysql>

You cannot modify information_schema to alter the foreign keys, you should use the ALTER table for that.


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