Navicat usage tutorial: how to identify duplicates with non-unique keys

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Navicat Premium is a management tool that can connect to multiple databases. It allows you to connect to MySQL, Oracle and PostgreSQL databases simultaneously with a single program, making it more convenient to manage different types of databases.

Most duplicate records fall into two categories: repetitive meaning and non-unique keys. In the MySQL article, how to identify and delete repetitive values involves repetitive meaning; in this article, we will discuss how to identify non-unique keys. This means that two records in the same table have the same key, but may or may not have different values and meanings.

Formation mechanism

Even well-designed databases can accumulate non-unique key duplicates. It is usually the result of importing data from external sources, such as text, csv, or excel files, as well as data sources. Even if you merge data from two different databases, if you combine each database in some way to generate a new key, duplicate keys may be created-- assuming, of course, that the new key column supports non-unique values. For example, it might be problematic to connect two numbers to generate a new key:

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