Abstract: The weak and strong holds of Full Functional Dependencies and Part Functional Dependencies under the null values environment are proposed in this paper. It is proved that for relational schema with null values, if it does not satisfy the weak hold of Full Functional Dependencies under the null values environment, then its any complete is not Full Functional Dependencies under the null values environment: if it satisfies the strong hold of Full Functional Dependencies under the null values environment then its any complete must be Full Functional Dependencie, under the null values environment Also given is a, algorithm which judges that a relation with null value, satisfies the strong and weak holds of Full Functional Dependencies. This paper lays clown the foundation for schema decomposition under the null values environment.