Feb 09, 2020 · Question 7 3 out of 3 points What does the “C” indicate in the ERD below? Selected Answer: Faculty members and administrators are the only types of employees in the system. Selected Answer : Faculty members and administrators are the only types of employees in the system ... Course Hero is not sponsored or endorsed by any college or ...
Feb 14, 2021 · Question 27 3 out of 3 points What does the “C” indicate in the ERD below? Selected Answer: Faculty members and administrators are the only types of employees in the system. Selected Answer : Faculty members and administrators are the only types of employees in the system ... Course Hero is not sponsored or endorsed by any college or ...
Oct 16, 2020 · Client-server architecture Question 13 What does the “C” indicate in the ERD below? 3 out of 3 points 3 out of 3 points 3 out of 3 points. 9/20/2020 Review Test Submission: Exam 1 ... Course Hero is not sponsored or endorsed by any college or university. ...
CSIS 325 – Lab 2 (ER Diagrams) Answer the following questions within this document, and upload this document to the assignment link in Canvas. 1. Using this completed instance diagram fill in the cardinality symbols for the ERD below. You will probably need to use a basic drawing tool within Word to draw the cardinalities.
Scuz helps you reconcile the different names, so the table only has one name per actual customer. But Scuz is a personable guy and he insists on identify his customers in the database by name. Your database knowledge tells you that such a design would: violate the referential integrity rule.
i.2 ii.3 iii.0 iv.0 (a)Frogen key: A foreign key is a way to enforce referential integrity within your Oracle database. A foreign key means that values in one table must also appear in another table. The referenced table is called the parent table wh … View the full answer
The primary key in the second table is: < >. birth date. the combination of both parents’ primary keys in the first table. the same primary key in the first table that identifies the child cat.
But, like many things in software development, there are a few different methods and standards that are available. For ERDs, there are several notation standards, which define the symbols used.
This can usually be expressed in words, or using “natural language”. Some examples are: “Record students, courses they enrol in, and teachers who teach the course”.
Cardinality represents the number of instances of an entity that exist in a relationship between two entities. This is often expressed as a number but could also be a symbol, depending on the style of diagram used. Common cardinality values are zero, one, or many. We’ll see some examples of cardinality later in this guide.
An attribute is a property of an entity or something that can be used to describe an entity. They are often represented as ovals, or as entries inside an entity. There are several different types of attributes represented on an ERD: Simple: an attribute that cannot be split into other attributes, such as a first name.
One to one: One record of an entity is directly related to another record of an entity. One to many: One record of an entity is related to one or more records of another entity. Many to many: Many records of one entity can be related to many records of another entity.
Relationship. A relationship in an ERD defines how two entities are related to each other. They can be derived from verbs when speaking about a database or a set of entities. Relationships in ERDs are represented as lines between two entities, and often have a label on the line to further describe the relationship (such as “enrols”, “registers”, ...
A weak entity is one that depends on a strong entity for existence. This means it has a foreign key to another entity. For example, an enrolment of a student may be a weak entity, as an enrolment cannot exist without a student.
How to Draw ER Diagrams 1 Identify all the entities in the system. An entity should appear only once in a particular diagram. Create rectangles for all entities and name them properly. 2 Identify relationships between entities. Connect them using a line and add a diamond in the middle describing the relationship. 3 Add attributes for entities. Give meaningful attribute names so they can be understood easily.
An attribute is a property, trait, or characteristic of an entity, relationship, or another attribute. For example, the attribute Inventory Item Name is an attribute of the entity Inventory Item. An entity can have as many attributes as necessary. Meanwhile, attributes can also have their own specific attributes. For example, the attribute “customer address” can have the attributes number, street, city, and state. These are called composite attributes. Note that some top level ER diagrams do not show attributes for the sake of simplicity. In those that do, however, attributes are represented by oval shapes.
There are three basic elements in an ER Diagram: entity, attribute, relationship. There are more elements which are based on the main elements. They are weak entity, multi valued attribute, derived attribute, weak relationship, and recursive relationship. Cardinality and ordinality are two other notations used in ER diagrams to further define ...
If an attribute can have more than one value it is called a multi-valued attribute . It is important to note that this is different from an attribute having its own attributes. For example, a teacher entity can have multiple subject values.
Recursive Relationship. If the same entity participates more than once in a relationship it is known as a recursive relationship . In the below example an employee can be a supervisor and be supervised, so there is a recursive relationship. Example of a recursive relationship in ER diagrams.
A relationship describes how entities interact. For example, the entity “Carpenter” may be related to the entity “table” by the relationship “builds” or “makes”. Relationships are represented by diamond shapes and are labeled using verbs.
They are widely used to design relational databases. The entities in the ER schema become tables, attributes and converted the database schema. Since they can be used to visualize database tables and their relationships it’s commonly used for database troubleshooting as well.