| 摘要 |
Database 20 consists of a field declaration table 22 defining data field types, a record declaration table 24 defining data record types, a field/record table 26 defining which record contains which data fields, a plurality of field data tables 30, one for each data field type identified in the field declaration table 24, and a plurality of record reference tables 28, one for each record identified in the record declaration table 24. Each record reference table 28 stores, for each field identified as associated with that record in field/record table 26, the data item references to data items stored in the corresponding field data table 30. Each data field is declared once and stored uniquely, regardless of how many data records contain that field. The data values for a data field are also stored uniquely. Duplication of stored data is thus avoided, and additions of new fields to the database are easily accomplished. Methods for the storage and retrieval of data items and records are described (figs. 3-7). |
