- What two conditions must valid entities meet?
- What is the difference between a composite key and a composite attribute?
- Is name a composite attribute?
- What is composite attribute?
- What is a composite attribute give examples?
- What is a simple attribute?
- What is a weak entity set?
- What two attributes must be contained in the composite entity?
- What is a composite entity when is it used?
- What is weak entity example?
- What is a strong entity?
- What is a strong or identifying relationship?
What two conditions must valid entities meet?
The entity must be existence-dependent on its parent entity.
The entity must inherit at least part of its primary key from its parent entity..
What is the difference between a composite key and a composite attribute?
Discuss the difference between a composite key and a composite attribute. How would each be indicated in an ERD? A composite key is one that consists of more than one attribute. … A derived attribute is an attribute whose value is calculated (derived) from other attributes.
Is name a composite attribute?
An attribute can be simple or composite. A simple attribute, such as grade, is one component that is atomic. If we consider the name in two parts, last name and first name, then the name attribute is a composite.
What is composite attribute?
Composite Attribute – An attribute composed of many other attribute is called as composite attribute. For example, Address attribute of student Entity type consists of Street, City, State, and Country. In ER diagram, composite attribute is represented by an oval comprising of ovals.
What is a composite attribute give examples?
Composite Composite attributes are not atomic because they are assembled using some other atomic attributes. A typical example of a composite attribute is a person’s address, which is composed of atomic attributes, such as City, Zip, and Street.
What is a simple attribute?
Simple attribute − Simple attributes are atomic values, which cannot be divided further. For example, a student’s phone number is an atomic value of 10 digits. Composite attribute − Composite attributes are made of more than one simple attribute. For example, a student’s complete name may have first_name and last_name.
What is a weak entity set?
In a relational database, a weak entity is an entity that cannot be uniquely identified by its attributes alone; therefore, it must use a foreign key in conjunction with its attributes to create a primary key. The foreign key is typically a primary key of an entity it is related to.
What two attributes must be contained in the composite entity?
What two attributes must be contained in a composite entity? Use proper terminology in your answer. The composite entity must at least include the primary keys of the (parent) entities it references.
What is a composite entity when is it used?
A composite entity is also known as a “bridge” entity. This “bridge” is used to handle the many-to-many relationships that the traditional entity could not handle. This entity lies between the two entities that are of interest and this composite entity shares the primary keys from both the connecting tables.
What is weak entity example?
A weak entity is one that can only exist when owned by another one. For example: a ROOM can only exist in a BUILDING. On the other hand, a TIRE might be considered as a strong entity because it also can exist without being attached to a CAR.
What is a strong entity?
Definition of Strong Entity The Strong Entity is the one whose existence does not depend on the existence of any other entity in a schema. It is denoted by a single rectangle. A strong entity always has the primary key in the set of attributes that describes the strong entity.
What is a strong or identifying relationship?
A strong or identifying relationship is when the primary key of the related entity contains the primary key of the “parent”.