BitmapCake!

If you are working frequently with MySql databases, it is more likely that you have got this error many times. If you're reading this article to find how to solve this error, you are in the right place. Keep on reading to know how you will get this error and how you can solve this without getting any headaches :)

For those who haven't seen this before, here is the full error message:

Error 1005: Can't create table '' (errno: 121)

I wanted to find an exact solution for this error and write it on my blog so that it will be a reference for others as well.

I referred to the MySql documentation and found this doc, and this error comes under the InnoDB errors section. So now we know this has something to do with InnoDB. Let's read the documentation a little more :)

As the documentation states;

14.21.5 InnoDB Error Codes

The following is a nonexhaustive list of common InnoDB-specific errors that you may encounter, with information about why each occurs and how to resolve the problem.

1005 (ER_CANT_CREATE_TABLE)
Cannot create table. If the error message refers to error 150, table creation failed because a foreign key constraint was not correctly formed. If the error message refers to error –1, table creation probably failed because the table includes a column name that matched the name of an internal InnoDB table.
….........

Reason for getting Error 1005: Can't create table (errno: 121):

You will get this error if you are trying to add a constraint name that is already used in somewhere else.

SELECT
    constraint_name,
    table_name
FROM
    information_schema.table_constraints
WHERE
    constraint_type = 'FOREIGN KEY'
AND table_schema = DATABASE()
ORDER BY
    constraint_name;