I need help answering a couple questions from Succeeding in Business Microsoft A

Question

I need help answering a couple questions from Succeeding in Business Microsoft Access 2013

Which of the following pairs of entities would require s one to-one, ne-to many and many-to-many relationship? Describe your answer a. Customers and orders b. States and state capitals c. College students and classes What is entity integrity? What is referential integrity? Should you enforce referential integrity in a database all the time? Why or why not? Name and describe the three types of anomalies that can occur in a database. What is the goal of normalization? Name and describe the three normal forms. What is a determinant? A partial dependency? A transitive dependency

Explanation / Answer

Entity integrity :

It is a mechanism to maintain a primary key where it serves as a unique key identifier for the rows in the table. This integrity has two properties for primary key.

1) the primary key is unique.

2) the primary key is not null.

The first property ensures that the primary key of each row uniquely identifies it.the secondary property ensures that the primary key has a value. This integrity will not allow insert and update operations to produce an invalid primary key.

Referential integrity:

It is a mechanism that the system provides to maintain foreign key. Foreign key is one table reference to a primary key in other table. This integrity has only one property for foreign keys.

1) a valid foreign key value must always reference an existing primary key or can contain a null.

A foreign key may contain a null it does not need to refer a primary key. This integrity has one rule where no operation like insert update deletes can create a non null foreign key unless a foreign exists

Using a referential integrity checks to a greatest extent and the performance is too slow because the database has to validate all the updates against the relationship it just makes things slower.

Anomalies are problems that arise in the date due to flaw in the database design. There are three types of anomalies, insertion , deletion , update anomalies.

Insertion anomalies occur when we try to insert data into a flawed table.

Deletion anomalies occur when we delete data from a flawed table.

Update anomalies occur when we change data in a flawed table.

The goal of normalisation is the process of organising the columns and tables of a relational database to reduce redundancy and to improve data integrity. It reduces and eliminates redundant data. In this data integrity is assured.

Types of normal forms

First normal form

Second normal form

Third normal form

   BCNF

In first normal form no two rows of data must contain repeating group of information i.e each set of the column must have a unique value such that multiple columns cannot be used to fetch the same row

In second normal form there must not be any partial dependencies of any column on primary key.

Third normal form applies that every non prime attribute of table must be dependent on primary key

Partial dependency : if a non prime attribute of the relation is getting derived by only a part of the composite candidate.

Transitive dependency : if a non prime attribute of the relation is geting derived by either another non primes attribute or the combination of part of the candidate key along with a non prime attribute then such dependency is transitive.

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.