What do you need to establish to ensure that there are no duplicate records in a database?

To ensure there are no duplicate records in a database, you need to establish a unique constraint or primary key on the relevant fields that should be unique. Implementing proper indexing can also help in quickly identifying duplicates. Additionally, data validation rules should be enforced at the application level to prevent duplicate entries before they even reach the database. Regular data audits can further help identify and clean any existing duplicates.