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 primary key of the many side migrates to the one side when transforming a one-to-many relationship.
False
• The truncate table statement in SQL creates a new table.
True
One property of a relation is that each attribute within a relation has a unique name.
True
A well-structured relation contains minimal redundancy and allows users to manipulate the relation without errors or inconsistencies.
False
The relational data model does, at this time, directly support subtype/supertype relationships.
True
When normalizing, the goal is to decompose relations with anomalies to produce smaller, well-structured relations.
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
An identifier assigned to an associative entity is also called a cross-relation key.
False
CASE tools can model more complex data relationships, such as ternary relationships.
False
There can be multivalued attributes in a relation.
False
Unlike columns, the rows of a relation may not be interchanged and must be stored in one sequence.
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 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.
False
• When transforming a unary many-to-many relationship to relations, a recursive foreign key is used.