Increasing number of Web Databases are available on the Web. The query for such databases is not just a keyword but a complex query and that search results are not a listing of general Web pages but a listing of records generated dynamically from the database behind the Web interface. This paper is a survey of 2,880 Web databases listed in Dnavi (Japanese National Diet Library). The first part analyses the form components TextInputFields, SelectMenu, RadioButtons and CheckBoxes for 880 "book search" DBs in Dnavi. The second part reports a strong connection between the input form and output data by analyzing the attribute names for 100 Web DBs chosen randomly from 1,541 DBs which accepts complex query.
