A Method for Finding All Candidate Keys of Relational Schema Based On Attributes Relative Table

In this paper, a new concept-Attributes Relative Table is proposed, operations are defined. and some property and theorem are studied. Based on the attributes relative table, an algorithm to find out all primary attributes of relation schema is proposed and an algorithm to find out all candidate keys of relation schema by means of composition of primary attributes is given. The time complexity of these algorithms are O（n2）.