Relational algebra

Question

Comments

IN C OPTION

A*B HAS FOUR COLUMNS TWO OF WHICH ARE CUSTOMER NAME. AS WHEN WE CROSS PRODUCT WE HAVE ALL COLUMNS.

SO WE DONT KNOW WHICH CUSTOMER NAME THEY ARE TALKING ABOUT

Answer 1

A) option A is inner join on Borrower and Depositor on customer-name so it will give all customers which having loan and account.

B) SELECT DISTINCT CUSTOMER-NAME FROM BORROWER WHERE CUSTOMER-NAME IN(SELECT CUSTOMER-NAME FROM DEPOSITOR);--> This will also return all different names of customers who taken loans.

C) this is cross product of two tables so it will give many redundant tuples. so this is wrong query according to question requirements.

Ans:C

Comments

But after it perform projection in which all redundant tuple removed????

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after projection duplicates will remove , not redundant(extra)