InnoDB mySQL unable to set "ON DELETE SET DEFAULT'. How to set?

Question

I am trying to create a table named EMPLOYEE. When I use the following statements without \"ON DELETE SET DEFAULT\" it is working.

Here is the Error I get with \"ON

Answer 1

You can't use ON DELETE SET DEFAULT or ON UPDATE SET DEFAULT with InnoDB

InnoDB and FOREIGN KEY Constraints
While SET DEFAULT is allowed by the MySQL Server, it is rejected as invalid by InnoDB. CREATE TABLE and ALTER TABLE statements using this clause are not allowed for InnoDB tables.

You may try ON DELETE SET NULL if it fits your needs

If ON UPDATE CASCADE or ON UPDATE SET NULL recurses to update the same table it has previously updated during the cascade, it acts like RESTRICT. This means that you cannot use self-referential ON UPDATE CASCADE or ON UPDATE SET NULL operations. This is to prevent infinite loops resulting from cascaded updates. A self-referential ON DELETE SET NULL, on the other hand, is possible, as is a self-referential ON DELETE CASCADE. Cascading operations may not be nested more than 15 levels deep

Here is SQLFiddle demo

Answer 2

You delete your parent table, which triggers the set default in the child. The DB tries to set the child records to their default 0. But there's no 0 record in the parent table, triggering the foreign key violation.

Check out the MySQL manual about foreign key constrains:

If you re-create a table that was dropped, it must have a definition that conforms to the foreign key constraints referencing it. It must have the right column names and types, and it must have indexes on the referenced keys, as stated earlier. If these are not satisfied, MySQL returns error number 1005 and refers to error 150 in the error message.

A few ideas:

• Better drop the tables and create it new with a well formed syntax.
• Make sure to add ENGINE=InnoDB; to your CREATE TABLE - command.
• Make sure InnoDB is enabled on your MySQL server. To verify this, try this command: SHOW VARIABLES LIKE 'have_innodb'; - if it returns a YES, then InnoDB is enabled.
• Check your command for upper- and lowercases in table- and fieldnames.
• Check this not only one the table you want to create, but also on the tables the foreign keys are referring to.
• Make sure your referred tables are properly indexed.

"When creating a foreign key constraint, MySQL requires a usable index on both the referencing table and also on the referenced table. The index on the referencing table is created automatically if one doesn't exist, but the one on the referenced table needs to be created manually (Source). Yours appears to be missing."

See MySQL Foreign Key Error 1005 errno 150

Answer 3

just use SET NULL rule and define trigger which will try to set to default value with exception handler if your default value has been deleted from master table