  Rapid growth of documents, web pages, and other types of text content is a
huge challenge for the modern content management systems. One of the problems
in the areas of information storage and retrieval is the lacking of semantic
data. Ontologies can present knowledge in sharable and repeatedly usable manner
and provide an effective way to reduce the data volume overhead by encoding the
structure of a particular domain. Metadata in relational databases can be used
to extract ontology from database in a special domain. According to solve the
problem of sharing and reusing of data, approaches based on transforming
relational database to ontology are proposed. In this paper we propose a method
for automatic ontology construction based on relational database. Mining and
obtaining further components from relational database leads to obtain knowledge
with high semantic power and more expressiveness. Triggers are one of the
database components which could be transformed to the ontology model and
increase the amount of power and expressiveness of knowledge by presenting part
of the knowledge dynamically
