Question

Translate the following ER diagram into an equivalent minimal storage relational design. (Be sure to include all necessary keys and foreign key references.)

keyOfA (attrOfA derivedAttr) A 1 dependsOn attrofwk Weak partialKey

Answer 1

this Er diagram basically constitute the following things
Lets talk about them which are as follows (simple and line wise explination here for the simplified design )

1. A : is a entity which simply reflect the obejct/things in the real world.

1.1-> attofA : is the number of the attribute associated with the A like taking an           
       example(person is entity and the id,name of the person is attribute)

"Person" is the entity and the (attribute of "person" is "person_id",                "person_name" etc)

   1.2-> Key of A : This simply means that the key which is used to uniquely identified            the whole entity by using the primary key concept.
           Example: as taken the above example of person , the "id" is used as            primary key ehich uniquely identified a person from the group .

   1.3->DerivedAttr-> This simply means the attributed which is derived from another attribute.
           Example; "DOB" is an attribute in person entity , then its age is    derived by using "dob" (:DATE OF BIRTH")

2. (1 TO MANY) : HERE "A" hold a relation to "WEAK" USING 1 TO MANY RELATION SCEME(totally dependent scheme)
               Example: like Customer having a two account at a given    branch (BANK AND ACCOUNT )

3. DependsON: This simply shows the relation ship for weak entity set means (here A holds            the relation with B by using a weak entity set type)
        Example: Just take an Example of (CUSTOMER<<BORROWS>>=lOANS)

           HERE cUSTOMER IS TOTALLY DEPEND(=) UPON THE LOAN USING A    BORROW DEPENDENCY OF THE WEAK entity set where the primary key of the    CUSTOMER IS reference for the LOAN AS A REFRENCE KEY (PRIMARY KEY OF    CUSTOMER , AS REFRENCE FOR LOAN)

4.partialKey: A foreign key's a field in a very table that's the first key of a connected table.    it's not absolute to unambiguously determine a row within the table it's in. A partial    key's one or additional fields that type a vicinity of a primary key. therefore a partial    key doesn't unambiguously determine a row, however will be combined with    another partial key

      Example:it Specify the key which is partally unique ,(used for the weak        attribute)

5: Weak:here double rectangle represent the weak entity set means
Example
( [LOAN]-<LOAN-PAYMENT.-[[PAYMENT]]
IN the same way WEAK IS DEPENDENT ON A FOR ITS association of the character set

6.AttributeOfWeak: attribute of the weak entity set is
just take an example here
Example
( [LOAN]-<LOAN-PAYMENT.-[[PAYMENT]]
here the payment is describe by usings its( payment number,amount,date) which constitute a weak entity set