A referential integrity constraint states ________
A、a foreign key attribute value must refer to an existing primary key value;
B、a foreign key attribute value can be NULL.;
C、both A and B;
D、neither A nor B
发布时间:2025-08-16 18:21:14
A、a foreign key attribute value must refer to an existing primary key value;
B、a foreign key attribute value can be NULL.;
C、both A and B;
D、neither A nor B