Differentiate between: Primary key and relationship

A primary key is a unique identifier for each record in a database table. It is used to ensure each record is uniquely identified and can be easily referenced by other tables. A primary key can consist of one or multiple columns, but the combination of columns must be unique.

A relationship, on the other hand, is a connection between tables in a database that allows data to be shared and accessed across multiple tables. Relationships are established based on common fields between tables, such as a foreign key that links the primary key of another table. Relationships can be one-to-one, one-to-many, or many-to-many, depending on the number of records that can be related between tables.