图书表Book的默认登记时间为当天,可用下列( )语句实现。
A.
Alter Table Book Add Constraint df_book Default(GetDate( )) For dJDate
B.
Alter Table Book Add Constraint df_book dJDate .Default(GetDate( ))
C.
.Alter Table Book. dJDate Add Constraint df_book Default(GetDate( ))
D.
Alter Table Book Add Constraint df_book Default(dJDate .GetDate( ))