Candidate key with
Candidate key
relationship uniquely sign of a neuron progenitor minimum attribute set
value on any two ancestral relationship instance on the property values (set) different candidate key
The primary key (primary Key)
if a relationship with a plurality of candidate keys, select one of them as the primary key
comprises a set of properties called super key candidate key (SuperKey)
if only the relationship between a candidate key, and the key candidates of relations contains all property, said the candidate key for the whole key (All-key)
Foreign key (Foreign Key)
If a property relation R (set) primary key Ks is F and the relationship between S correspondence, i.e., the relationship between the value corresponding to the Ks is R in ancestral values and the relationship between S Meta progenitors in F, and called this property (set) F foreign key relationship R
The foreign key is not necessarily the same name as the corresponding primary key
by one or more attributes which uniquely identify the values in the relational model tuples of any
