You are asked from a company to review and fix their database because they noticed some irregularities in their customer's data

Computer Science Oct 16, 2020

You are asked from a company to review and fix their database because they noticed some irregularities in their customer's data. Some clients are inserted two (2) or three (3) times.
What steps you will follow to fix and make sure their database will never have double entries again?
Give detail explanations of the steps you will need to take so that the database is up and running.
Have in mind that a downtime is not allowed so you cannot just "Take the database offline"