高階ICT-DBAS-016
The same home address is typed into every loan row for one borrower. Which problem does that create?
A. Repeating the address always makes the primary key unique.
B. An update can change one copy and miss the others, so the stored addresses disagree.✓ 答案
C. The repetition is required for referential integrity.
D. Repeating the address removes any chance of a typing error.
解說
Redundant copies drift apart when only one is edited. A borrower table held once, and linked by a key, avoids that.