Review Exercice 1/ PART 1
10) The truncate table statement in SQL creates a new table.
FALSE
12) An anomaly is a type of flaw in the database server.
FALSE
15) When transforming a weak entity, one should create one relation with both the attributes of the strong entity and the attributes of the weak entity.
FALSE
16) The primary key of the many side migrates to the one side when transforming a one-to-many relationship.
FALSE
17) When transforming a one-to-one relationship, a new relation is always created.
FALSE
19) An identifier assigned to an associative entity is also called a cross-relation key.
FALSE
2) Unlike columns, the rows of a relation may not be interchanged and must be stored in one sequence.
FALSE
20) When transforming a unary many-to-many relationship to relations, a recursive foreign key is used.
FALSE
21) The relational data model does, at this time, directly support subtype/supertype relationships.
FALSE
24) A co-dependency is a constraint between two attributes or two sets of attributes.
FALSE
6) The entity integrity rule states that a primary key attribute can be null.
FALSE
7) In the relational data model, associations between tables are defined through the use of primary keys.
FALSE
CASE tools can model more complex data relationships, such as ternary relationships.
FALSE
1) The columns of a relation can be interchanged without changing the meaning or use of the relation.
TRUE
11) A well-structured relation contains minimal redundancy and allows users to manipulate the relation without errors or inconsistencies.
TRUE
14) When a regular entity type contains a multivalued attribute, two relations are created.
TRUE
18) If an identifier is not assigned, the default primary key for an associative relation consists of the two primary key attributes from the other two relations.
TRUE
22) When normalizing, the goal is to decompose relations with anomalies to produce smaller, well-structured relations.
TRUE
23) A relation in fifth normal form may not contain any anomalies.
TRUE
3) Sample data are useful for developing prototype applications and for testing queries.
TRUE
4) The allowable range of values for a given attribute is part of the domain constraint.
TRUE
5) All values that appear in a column of a relation must be taken from the same domain.
TRUE
8) A referential integrity constraint is a rule that maintains consistency among the rows of two relations
TRUE
9) A cascading delete removes all records in other tables associated with the record to be deleted.
TRUE
