Exercise: Student Grades You are working an on application to store student data

Question

Exercise: Student Grades You are working an on application to store student data for the CECS department. Based on the data in the following table:

o Diagram each functional dependency using arrows as we showed you in class.

• Draw the relation scheme for a lossless join decomposition of this table.

SID 142 142 123 857 857 456 217 CID CPS196 CPS114 email bart@fox.com bart@fox.com milhousefox.com CPS196 lisa(@fox.com lisa(@fox.com ralph@fox.com Maggie@fox.com rade name Bart Bart Milhouse Lisa Lisa Ralph Maggie B+ A+ A+ CPS196 CPS130 CPS114 CPS196 B-

Explanation / Answer

Remove all of the phone number fields from theContacts relation. Create a new scheme that has theattributes of the phone number structure (phone typeand number).2.The Contacts relation has now become a parent so weadd a surrogate key and copy it into the new scheme.There is now a one-to-many relationship betweenContacts and PhoneNumbers.3.To identify each phone number, we need to know atleast who it belongs to and what type it is. However, aperson can have two cell phones so all three attributesare needed for the PK. Since this is not a parent relation,the PK size doesn’t matter.

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