When applying the Relational model to the conceptual schema based on the Entity-Relationship model, each weak entity will generate a table that will include all its attributes. To this table, the attributes that are the primary key of the strong entity with which it is related will be added. These added attributes constitute a foreign key that references the strong entity. Then, a primary key will be chosen for the created table. True or false? True False.
A double diamond represents a weak relationship. True or false? _____" True False.
Attributes associated with a relationship are always represented by an ellipse, their identifier inside it, and a dashed line that connects the ellipse to the diamond of the relationship. True or false? True False.
Where would the issuance date of an invoice be stored in a conceptual schema based on the Entity-Relationship model? In the CUSTOMER entity, with NUM_INVOICE added to that entity. In the INVOICE entity. In the relationship that associates the INVOICE and CUSTOMER entities. All of the answers are correct.
That normal form that establishes that every determinant is a candidate key, among other restrictions, is called: 2NF 4NF BCNF 3NF.
If we establish a simile with Object-Oriented Programming, we can say that the concept of entity is analogous to that of a class. True False.
For a table to be in 1NF, all non-key attributes must depend functionally on the primary key. True False.
When we generate the conceptual schema of the database and later simplify it, we will look for it to contain only... Unary relationships. Binary relationships. Double relationships. Ternary relationships.
In a relationship, if the existence of each occurrence of one of the entities requires at least one occurrence of the other entity, we are facing a mandatory, total, or full participation relationship. True or false? True False.
The types of identification and existence dependencies correspond to: Weak entities. Hierarchies. Candidate and primary keys. Strong entities.
Indicate which statement is correct: All primary keys are usually formed from composite attributes. A primary key must be atomic and multivalued. Primary keys must be multivalued attributes. The primary key can be composed of several attributes.
Between entities, if a strong entity instance disappears and the dependent weak entity instances that depend on the first also disappear, considering that each weak entity occurrence can be identified by itself, we will have: A weak entity. An identification dependency. A specialization hierarchy. An existence dependency.
Obtaining the Conceptual Schema of a database is achieved in the Design Phase. True or false? True False.
If when representing an entity in the Entity-Relationship model, none of the attributes written inside ellipses are underlined, we are dealing with: A specialization hierarchy. A strong entity. A weak entity, if represented with a double rectangle. A set of composite attributes.
If in a table, an attribute depends functionally on a set of attributes and there is no possibility that it depends functionally on a subset of them, we say that we are facing: A transitive dependency. A functional dependency. All answers are correct. A complete functional dependency.
In the Entity-Relationship model, key attributes are represented as... With their identifier underlined, next to a black circle. With their identifier underlined, inside an ellipse. With an asterisk next to the key identifier. No answer is correct.
If we find the label (0,1) in the cardinality of an entity, it means that the entity may not participate in the relationship or may participate at most once. True False.
Who defined the relational model and published a series of rules for the normalization of relational databases? Peter P. Codd 1970. No answer is correct. Edgar Frank Codd 1970. Peter P. Chen 1979.
A primary key is a... Mandatory attribute. Derived attribute. Optional attribute. Composite attribute.
Indicate which statement is incorrect regarding candidate keys: Every primary key is also a candidate key. Every alternate key is also a candidate key. A candidate key is a primary key that also satisfies the minimality property. Every relation has at least one candidate key.
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