A deductive database consists of collection of stored facts and deductive rules. It can answer queries based on logical deduction from the stored facts and general rules. A deductive database has both a declarative meaning(semantics) and a procedural meaning. The declarative semantics of a deductive database provides a definition of the meaning of the program in a manner which is independent of procedural considerations, context-free, and easy to manipulate, exchange and reason about. This paper investigates various declarative semantics of deductive databases, dicusses related computational issues, and suggests another declarative semantics for deductive databases which is more practical than others.