Is the primary key necessary for MySQL?

The primary key of MySQL is necessary. Adding a primary key to all tables is a good habit when using the database. The primary key will help users avoid introducing duplicate data problems when migrating data.

What is a primary key?

Each row in the table is uniquely determined by the primary key (PK). When you create a table, you must specify the columns that make up the primary key. These columns are called primary key columns. The primary key column must have a value. You must ensure that the combination of values ​​for the primary key columns uniquely identifies a row. During subsequent use, the type of the primary key column cannot be changed.

Take HybridDB for MySQL as an example:

HybridDB for MySQL has no sharing between logical partitions, so uniqueness can be guaranteed within a partition, but the partitioning Ranges will not be able to maintain all database and table constraints, even uniqueness constraints.

Using the AUTO_INCREMENT column can ensure global uniqueness. (Recommended course: MySQL Tutorial)

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