Exam 6: Developing Data Models for Business Databases

The Identification Dependency Rule states that each identifying relationship (denoted by a solid relationship line)adds a component to the __________ of the weak entity.

Figuer: -The table WRITTEN-BY obtained in converting the ERD diagram to a relational database will contain the following number of attributes:

Figuer: -Assuming that we do not use the rule(s)that avoid null values in tables in converting the ERD diagram to a relational database,title will appear as a foreign key the following number of times:

In order to make it easier to reference an entity type after conversion to a table,a weak entity is sometimes changed to a strong entity and the associated identifying relationships are changed to nonidentifying relationships.

When performing the identification of primary keys,ideally,primary keys should be _______ and _________.

Even if you create design documentation and perform checks for design errors during the design process,you will still need to conduct _______________ to ensure adequate design documentation and lack of design errors.

Design errors are more difficult to detect than diagram errors because they involve the meaning of the items on a diagram instead of just the structure of the diagram.

A common refinement of a data model is to transform an _________ into an entity type.This is useful when the database should contain more than just the identifier of an entity.

Whenever an entity can exist in multiple states,a generalization hierarchy should be used.

One important reason for documenting design decisions it to _______________ those decisions to others.

Primary keys for entity types:

In data modeling:

Both SQL:1999 and the Relational Model directly support generalization hierarchies.

Design documentation:

Converting an optional 1-M relationship into a table results in easier query formulation and faster query execution.

When a 1-1 relationship is converted into two foreign keys,if the relationship is optional for one of the entity types,the corresponding foreign key may be eliminated.

During narrative problem analysis you should look for nouns that have additional sentences describing their properties.The properties often indicate _________ of entity types.

Relationships often appear as ________ connecting nouns previously identified as entity types.

In converting a generalization hierarchy in an ERD to a relational database design,the parent and the subtypes at every level each become a table.

Figuer: -Assuming that we do not use the rule(s)that avoid null values in tables in converting the ERD diagram to a relational database,the number of attributes in the primary key of the table SUBCOMMITTEE is: