Chapter 4 BMI410

What is a full key functional dependency?

When a primary key functionally determines the column of a relation and no separate component of the primary key partially determines the same column.

What is a transitive functional dependency?

When non-key columns functionally determine other non-key columns of a relation.

How does a deletion anomaly occur?

- When a user wants to delete data about a real-world entity is forced to delete data about another real-world entity. -You cannot delete something without also deleting something else without losing the information all together. - Terminal C and SWA (class activity)

How does an insertion anomaly occur?

-When a user wants to insert data about one real-world entity is forced to enter data about another real-world entity. -For instance, if you have a group of students and courses you cannot add a new course unless we have at least one student enrolled in that course to the table.

What is the purpose of designer-added entities, tables, and keys?

Entitles not called for by the original requirements, added by the database designer; they result in designer-added tables. Designer added keys are primary keys of designer-added tables, created by the database designer.

What does normalization entail?

Normalization generally entails splitting one database table into two simpler tables.

What is denormalization and what is its purpose?

Reversing the effect of normalization by joining normalized relations into a relation that is not normalized. -Example you may have a copy of a normalized version of the relational database which has all insertions, modifications, and deletions on the data done in order to avoid update anomalies. -However, at the same time have a denormalized copy of the database for quicker retrievals.

What is a functional dependency?

When the value of one or multiple columns in each record of a relation uniquely determines the value of another column in that same record or relation. AB

How does a modification anomaly occur?

When you modify one value you must do the same modification multiple times. Modification anomalies are so named because they are generated by the addition of, change to, or deletion of data from a database table.

What are the three update operations?

-Inserting data into the relations -Modifying existing data or changing the existing data in the relations -Deleting data from the relations.

Give the definition of 1NF.

A table is in 1NF (normal form) if each row is unique and no column in any row contains multiple values from the column's domain.

Give the definition of 2NF.

A table is in 2NF (normal form) if it is in 1NF and does not contain partial functional dependencies.

Give the definition of 3NF.

A table is in 3NF if it is in 2NF and does not contain transitive functional dependencies.

What is redundant data?

It is when a relation stores multiple instances of the same data referring to the same occurrence. Duplicate information in a database.

What is a partial functional dependency?

When a column of a relation is functionally dependent on a component of a composite primary key.