Can mysql primary key be empty?

mysql primary key cannot be empty, because when creating or changing a table, you can create a primary key by defining a "PRIMARY KEY" constraint, and a table can only have one primary key constraint, and the columns in the primary key constraint cannot be empty. Value, because primary key constraints ensure unique data, identity columns are often defined.

The database primary key refers to a column or a combination of columns in the table, and its value can uniquely identify each row in the table. Such a column or columns become the primary key of the table, through which the entity integrity of the table is enforced. When creating or changing a table, you can create a primary key by defining a PRIMARY KEY constraint. A table can only have one primary key constraint, and the columns in the primary key constraint cannot be null. Since the primary key constraint ensures unique data, identity columns are often defined. .

The role of the primary key:

1. As can be seen from the above definition, the primary key is used to uniquely identify a row of data in the database table.

2. As an object that can be effectively referenced by foreign keys.

Can the mysql primary key be empty?

Attention! The primary key can never be null!

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