| 摘要 |
PURPOSE:To automatically extract the joint information between tables without any leaking even in the database composed of many tables by retrieving the database only by describing the conditions concerning the column of respective tables even when a user does not have the knowledge concerning the structure of the database which is a retrieval object and the detailed knowlledge concerning the joint information between the tables. CONSTITUTION:This system has a joint information holding means 4 to hold the joint information between tables of a database, a joint conditions imperting means 1 to obtain the joint information from the joint information holding means 4 and output a retrieval expression to add the joint information with the table retrieval expression as an input and a database control means 2 to perform the retrieval of a database storage means 3 while the retrieval expression is received, and has a joint information extraction means 5 to extract the joint informaiton between the tables of the database storage means 3 from the database control means 2 and send the extracted joint information to the joint information holding means 4. |
