BACHELOR OF BUSINESS ADMINISTRATION

Detailed explanation-1: -A primary key is a field in a table which uniquely identifies each row/record in a database table. Primary keys must contain unique values. A primary key column cannot have NULL values.

Detailed explanation-2: -Primary key constraints NULL values are not allowed. If the column(s) contain NULL values, the system will not add the primary key constraint. See ALTER TABLE statement for more information. A table can have at most one PRIMARY KEY constraint.

Detailed explanation-3: -The primary key attribute cannot be optional (i.e., have null values). The primary key cannot have repeating values. That is, the attribute may not have more than one value at a time for a given entity instance is prohibited. This is known as the No Repeat Rule.

Detailed explanation-4: -A primary key cannot have null values. We can say that primary Keys are NOT NULL by nature. A primary key is UNIQUE. The primary key attribute cannot contain duplicate values (there cannot have two records having the same value of the primary key field).

Detailed explanation-5: -The statement that is false regarding primary key is: Only parent tables must have a primary key. Because, a primary key must be unique, it can be made up of multiple attributes and it must not contain a null value.