A、What B、That C、This D、Which
A、What B、That C、This D、Which
A、A.COL1 will accept NULL values and can be referenced in another table's foreign key specification. B、B.COL1 will not accept NULL values and cannot be referenced in another tables foreign key specification. C、C.COL1 will not accept NULL values and can be referenced in another tables foreign key specification. D、D.COL1 will accept NULL values and cannot be referenced in another tables foreign key specification.
A、Liquids with different viscosities will always have the same specific gravity B、Liquids with different viscosities will never have the same specific gravity C、Viscosity and specific gravity are directly proportional D、Viscosity and specific gravity are not related in that one does not define or limit the other