Parsing mysql database restoration Error: (mysql Error Code: 1005 errno 121)

The reason is that the primary key must be unique, that is, there may be duplicates in the database with the current restored database. a restriction that Foreign Keys shoshould be uniquely named throughout the database, an effective method is to clear the original database and then create and restore it.

The reason for this is that the newly installed mysql ibdata1 backup file was changed to the ibdata1 backup file of the previous database. I wanted to use this method to forcibly restore it, but I didn't do it, as a result, an error occurred while restoring the database with the backup SQL file. You can restore the replaced ibdata1 file back.