Define the term Superkey

The following Figure 1 shows some portion of the database of a company on medical claims.  Refer to the relations, Claim and ClaimType shown in the diagram and answer the following questions.  

 



 

                 

a)    
How many tuples are there in the ClaimType relation?                        [2 Marks]

 

b)    
What is the degree of the ClaimType relation?                                     [2 Marks]

 

c)    
The Superkey for the Claim relation is provided as follows:  

 

claimNo,

{claimNo, dateFrom},

{claimNo, empID},

{dateFrom, empID, claimCode}

 

                Define the term Superkey                                                                   [4 Marks]

 

d)    
From the superkey listed above in (c), determine which is candidate key and which is not.                                                                             [4 Marks]

 

e)    
From the candidate key listed in (d), determine the primary key and the alternate key.          [4 Marks]

 

f)     
List the foreign keys.                                                              [4 Marks]