Tables without primary keys are largely unusable in a relational database because they cannot be joined to. A primary key should be specified at
table creation to guarantee that all its records have primary key values.
Noncompliant code example
CREATE TABLE employee
(
employee_id INTEGER NOT NULL,
first_name VARCHAR2(42) NOT NULL,
last_name VARCHAR2(42) NOT NULL
);
Compliant solution
CREATE TABLE employee
(
employee_id INTEGER PRIMARY KEY,
first_name VARCHAR2(42) NOT NULL,
last_name VARCHAR2(42) NOT NULL
);
