BDI302cXuất hiện trong 1 đề thi
Suppose a registration website creates data with the following fields for each person registered (note: if the user does not input a value, NULL is stored instead): Name, Date, Address, and Account Number. Which constraint have we placed on the Account Number field for the end-of-year collection?
Các lựa chọn
AAccount should have at most n digits.
BIf we had n duplicate Account Numbers then we will remove n-1 duplicate fields.
CThere are no constraints.
DAccount Number should be unique.