DENG Topics 1 & 2

A foreign key imposes a specific kind of integrity to related tables. What is the name of this integrity?

• Entity

• Referential

• Data

• Schema

Which of the following cannot be blank (null)?

• Foreign key

• Secondary key

• Primary key

• none of the above can be null

Which of the following are requirements of a relational database?

 

 

• All nonkey attributes must describe a quality of the item identified by the primary key

• Primary keys cannot be null or empty

• Foreign keys (if not empty) must be a primary key in another table

• All of the above

Which of the following is FALSE regarding the use of relational table ?

 

 

• To build a query, you must know the order of all rows and columns in each relational table

• All data values in a column must conform to the same data format

   

• Each cell in a relational table can contain only one value

• The tables in a relational database are linked to each other through primary and foreign keys

Which of the following describes referential integrity?

 

• A primary key of a relational table must not contain a null value

• The value for a foreign key attribute must either be null or match one of the data values in the table in which the attribute is a primary key

   

• Multiple facts must not be stored in a single cell

• Referential integrity is a principle that prevents the use of redundancy, avoids null values, and creates a minimal database