MariaDB Essentials

Dealing with duplicates and consistency errors

Our product table does not have any UNIQUE index. However, at least one column should contain a unique value; in fact, it would be rather uncommon to have several products with the same name. So, let's add a UNIQUE index:

ALTER TABLE product ADD UNIQUE INDEX unq_name (name);

Now that we have a UNIQUE index, we can use it as an example to discuss how we can deal with duplicates with MariaDB.

Suppose that we want to add a new product, or modify an existing product. In both cases, there is a possibility that the new product name is already in use, causing a conflict. MariaDB supports several statements to automatically handle this conflict:

Syntax	Behavior
INSERT	MariaDB will simply reject the new ...