DBI202Xuất hiện trong 2 đề thi
Regarding difference between a primary key vs. unique key, which of the following is false?
Các lựa chọn
AThere can be only one unique key for a table
BA primary key is a key that uniquely identifies each record in a table but cannot store NULL values
CA unique key prevents duplicate values in a column and can store NULL values.
DOnly one primary key is allowed to use in a table.