CGS2545 T/F
True
A primary key is an attribute that uniquely identifies each row in a relation.
True
When a regular entity type contains a multivalued attribute, two relations are created.
False
• The truncate table statement in SQL creates a new table.
True
A cascading delete removes all records in other tables associated with the record to be deleted.
False
A composite key consists of only one attribute.
True
All values that appear in a column of a relation must be taken from the same domain.
False
An anomaly is a type of flaw in the database server.
False
CASE tools can model more complex data relationships, such as ternary relationships.
False
There can be multivalued attributes in a relation.
False
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.
True
A well-structured relation contains minimal redundancy and allows users to manipulate the relation without errors or inconsistencies.
False
The primary key of the many side migrates to the one side when transforming a one-to-many relationship.
False
The relational data model does, at this time, directly support subtype/supertype relationships.
False
Unlike columns, the rows of a relation may not be interchanged and must be stored in one sequence.
True
When normalizing, the goal is to decompose relations with anomalies to produce smaller, well-structured relations.
False
• When transforming a unary many-to-many relationship to relations, a recursive foreign key is used.
False
An identifier assigned to an associative entity is also called a cross-relation key.
True
One property of a relation is that each attribute within a relation has a unique name.
True
• A referential integrity constraint is a rule that maintains consistency among the rows of two relations.
False
• Data integrity consists of powerful operations to manipulate data stored in relations.
True
• Data structures include data organized in the form of tables with rows and columns.
True
• 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.
False
• In the relational data model, associations between tables are defined through the use of primary keys.
True
• Sample data are useful for developing prototype applications and for testing queries.
True
• The allowable range of values for a given attribute is part of the domain constraint.
True
• The columns of a relation can be interchanged without changing the meaning or use of the relation.
False
• The entity integrity rule states that a primary key attribute can be null.
False
• When transforming a one-to-one relationship, a new relation is always created.
