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91a) i. Selecting good primary keys is important for the efficiency and effectiveness of a database. For the given entity relationship diagram (ERD), solve all problems with regards to primary key selection by proposing alternative primary key(s) as a replacement. Draw the resulting ERD. CUSTOMER PURCHASE_LOG PRODUCT PK CUS_FNAME PK, FK1CUS_FNAME PK PROD_SERIAL_NUM PROD QUANTITY PK CUS_LNAME PK, FK2 CUS_LNAME PK PK CUS_INIT has-PK, FK3 CUS INIT listed in PROD_COLOUR PK CUS PHONE PK, FK3 CUS_PHONE PROD_NAME CUS EMAIL PK, FK3 PROD_SERIAL_NUMBER PROD_COST CUS_BANK_ACC PK, FK4 PROD QUANTITY PURCHASE_QUANTITY PURCHASE TOTAL (5 marks) Additional Instructions: You are allowed to draw the ERD by hand on a piece of paper or create the ERD using diagrams.net You need to write/include your index number beside the diagram before uploading the image file on eLearn Image file format should preferably be in JPEG or PNG Upload the ERD image in the Files box (Max. size is 4 GB)