A method and system for identifying schemas of web databases is provided. A schema matching system generates a mapping between an interface schema and a result schema of a web database, which is used to represent the underlying database schema. The schema matching system also generates a mapping of the interface attributes and the result attributes of the web database to global attributes of a global schema whose semantics are known. Using these mappings, a search engine service can formulate queries using the global attributes, map those queries to the corresponding interface attributes, submit the query, and retrieve the values from the result attributes that correspond to the desired global attributes.