Entity relationship diagram for address book

Address Book Application Design

entity relationship diagram for address book

of a few different contact information programs like Address Book, gmail contacts, etc. I use this VS plugin: NORMA that will also generate a schema for you too. actually belongs to relationship between person and company entities. Are you considering addresses as entities in themselves, or as merely free text . Address book database entity-relationship diagram for, modeled as index cards, modeled as table, Administrative safeguards, Advanced. Link: ERD Diagram. 6. Table Design & Relationships• The design of each of the tables and their PhoneList Table• This table connects the Phone table to the Contact table as a bridge entity between the two. The contact list database also serves as an e-mail address book as well as a phone book.

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entity relationship diagram for address book

Get unlimited access to videos, live online training, learning paths, books, tutorials, and more. No credit card required The Entity Relationship Model At a basic level, databases store information about distinct objects, or entities, and the associations, or relationships, between these entities.

Address book dfd ( Data Flow Diagram)

For example, a university database might store information about students, courses, and enrollment. A student and a course are entities, while an enrollment is a relationship between a student and a course. Similarly, an inventory and sales database might store information about products, customers, and sales. A product and a customer are entities, while a sale is a relationship between a customer and a product.

A popular approach to conceptual design uses the Entity Relationship ER model, which helps transform the requirements into a formal description of the entities and relationships that appear in the database.

street address - Building a Contact Database - Need a little schema inspiration - Stack Overflow

In the ER diagram, an entity set is represented by a rectangle containing the entity name. An entity set is represented by a named rectangle We typically use the database to store certain characteristics, or attributes, of the entities. In a sales database, we could store the name, email address, postal address, and telephone number for each customer.

Attributes describe the entity they belong to. An attribute may be formed from smaller parts; for example, a postal address is composed of a street number, city, ZIP code, and country.

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Some attributes can have multiple values for a given entity. For example, a customer could provide several telephone numbers, so the telephone number attribute is multivalued.

entity relationship diagram for address book

Attributes help distinguish one entity from other entities of the same type. We could use the name attribute to distinguish between customers, but this could be an inadequate solution because several customers could have identical names.

To be able to tell them apart, we need an attribute or a minimal combination of attributes guaranteed to be unique to each individual customer. The identifying attribute or attributes form a key. In our example, we can assume that no two customers have the same email address, so the email address can be the key. However, we need to think carefully about the implications of our choices.

For example, if we decide to identify customers by their email address, it would be hard to allow a customer to have multiple email addresses. Any applications we build to use this database might treat each email address as a separate person, and it might be hard to adapt everything to allow people to have multiple email addresses.

Clearly, there may be several possible keys that could be used to identify an entity; we choose one of the alternative, or candidate, keys to be our main, or primary, key. You usually make this choice based on how confident you are that the attribute will be non-empty and unique for each individual entity, and on how small the key is shorter keys are faster to maintain and use. Attributes comprising the primary key are shown underlined. The parts of any composite attributes are drawn connected to the oval of the composite attribute, and multivalued attributes are shown as double-lined ovals.

Similarly, a product price could be a positive rational number.

Entity Relationship Diagrams

Attributes can be empty; for example, some customers may not provide their telephone numbers. You should think carefully when classifying an attribute as multivalued: This approach is helpful in that it allows you as a manager or leader to better understand what is going on within the organization so you can make changes as necessary. When you are caught up in the day to day process of running a business, you might not have time to step back and see how things are really working.

Making time for entity relationship diagrams will force you to look objectively at the relationships that are currently in place so you can determine how they can be improved. You can download business strategy templates and checklists from our website. Different Types of Relationships There are a number of possible types of relationships within any organization — whether you are talking about data that may exist, processes that work with other processes, or even employees with their various supervisors.

You will want to identify the types of relationships that you are dealing with so you can then make the best decisions going forward based on the current status of the organization.

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In general, there are three different kinds of relationships you will observe — One to One, One to Many, and Many to Many. While relationships within organizations are often complex and even confusing, putting each of them into one of these three categories is a good start at getting a handle on things.

One to One In this relationship, one entity is related directly to one other entity. This is the simplest and most-obvious form of a relationship.

entity relationship diagram for address book

Many times, a One to One relationship will be seen in data collection, such as information that you have on your customers. If you have names and email addresses within a database that you use to market to your existing customers, those two entities have a One to One type of relationship. Each name has an email address associated with it, and vice versa.

In this way, One to One relationships are rather easy to understand. They may also add and edit information about how to view a contact field. User Interface The User Interface From the user interface, the user can go to his own private address book, a group address book, or a public address book -- if he has permission to view them.

entity relationship diagram for address book

Furthermore, if he has the right permissions, he may edit the address books as well. At the address book, he may sort and search for contacts and view them. He may also add, edit, and delete contacts. Finally, he may manage the contact fields he would like to use in his address book. Contacts' e-mail addresses are linked with an HTML mailto tag, so the user may directly e-mail contacts by clicking on their e-mail addresses.