A database processing method for defining and operating data of file reference type which references a file. A column data insert request for specifying position information indicative of a storage location of a file and watch information for watching the file is received from a database client. A request for watching a file indicated by the position information is issued in accordance with the watch information. The position information and the watch information are stored in a database. The foregoing operations permit data in an external file placed outside a database to be treated as data equivalent to ordinary column data stored in the database to improve the integrity of the database.