Primary key

Definition

A Primary Key uniquely identifies each row in a table. It combines the properties of NOT NULL and UNIQUE, and a table can have only one primary key (though it may span multiple columns as a composite key).

Example

CREATE TABLE employees (
  id NUMBER PRIMARY KEY,
  name VARCHAR2(50)
);

Why It Matters for Testing

Primary keys are what foreign keys reference to build relationships between tables; testers rely on them to reliably identify and verify a specific record across multiple related tables.