Description:
This issue is very similar to that reported in https://bugs.mysql.com/bug.php?id=88718, however it affects the table name reported in the foreign key, not the column name, and this does appear to be a regression with MySQL 8.0 that does not occur in version 5.7. When calling SHOW CREATE TABLE, the table name reported in a foreign key constraint comes out as all lower case, when on a case-insensitive filesystem with lower_case_table_names=2. This does not occur in MySQL server 5.7.
How to repeat:
First establish that the database is on a case-insensitive filesystem with lower_case_table_names=2:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 30
Server version: 8.0.17 MySQL Community Server - GPL
Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> show variables like 'lower_case_table_names';
+------------------------+-------+
| Variable_name | Value |
+------------------------+-------+
| lower_case_table_names | 2 |
+------------------------+-------+
1 row in set (0.00 sec)
Create two tables very similar to those mentioned in the fourth or so comment in https://bugs.mysql.com/bug.php?id=88718, except make the casing of the parent table name also mixed case:
CREATE TABLE `Table_One` (
`Id` INTEGER PRIMARY KEY
);
CREATE TABLE `table_two` (
`TABLE_ONE_ID` INTEGER,
FOREIGN KEY (`TABLE_ONE_ID`) REFERENCES `Table_One` (`Id`)
);
we can see that SHOW CREATE TABLE `table_two` reports the name of `Table_One` using all lower case:
mysql> SHOW CREATE TABLE `table_two`;
+-----------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-----------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| table_two | CREATE TABLE `table_two` (
`TABLE_ONE_ID` int(11) DEFAULT NULL,
KEY `TABLE_ONE_ID` (`TABLE_ONE_ID`),
CONSTRAINT `table_two_ibfk_1` FOREIGN KEY (`TABLE_ONE_ID`) REFERENCES `table_one` (`Id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci |
+-----------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
Running the identical steps / configuration for MySQL 5.7 yields the correct result:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.7.27 MySQL Community Server (GPL)
Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> CREATE TABLE `Table_One` (
-> `Id` INTEGER PRIMARY KEY
-> );
Query OK, 0 rows affected (0.04 sec)
mysql>
mysql> CREATE TABLE `table_two` (
-> `TABLE_ONE_ID` INTEGER,
-> FOREIGN KEY (`TABLE_ONE_ID`) REFERENCES `Table_One` (`Id`)
-> );
Query OK, 0 rows affected (0.04 sec)
mysql> SHOW CREATE TABLE `table_two`;
+-----------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-----------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| table_two | CREATE TABLE `table_two` (
`TABLE_ONE_ID` int(11) DEFAULT NULL,
KEY `TABLE_ONE_ID` (`TABLE_ONE_ID`),
CONSTRAINT `table_two_ibfk_1` FOREIGN KEY (`TABLE_ONE_ID`) REFERENCES `Table_One` (`Id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 |
+-----------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
