Fundamentals of databases

Question 2

Define Atttribute

Answer 2

• A property or characteristic of an entity in a database. It represents a single piece of data about the entity, such as a column in a table.
• For example, in a table representing students, attributes might include Name, Age, and StudentID.

Question 2

Define Primary Key

Answer 2

• A unique identifier for a record in a table, that allows for each record to be uniquely distinguished from all others. Each value must be unique.

Question 3

Define Composite Primary Key

Answer 3

• A primary key that consists of two or more attributes combined to uniquely identify a record in a table, used where one primary key is not enough to distinguish each record.

Question 4

Define Foreign Key

Answer 4

• An attribute in a table which establishes a relationship with the primary key of another table. It is used to enforce referential integrity, ensuring the value of the foreign key of a record matches its primary key it the related table.

Question 5

First Normal Form Conditions

Answer 5

• Columns are not allowed to contain atomic values (multiple values)
• Remove duplicate rows, usually achieved using a primary key,

Question 6

Second Normal Form Conditions

Answer 6

• The table must be in first normal form.
• ## There must be no partial dependencies (all non-key attributes must depend on the primary key, cannot occur with composite primary keys).