| 摘要 |
Schema deriving module 1 generates a relational schema 6 from a subschema 5, in accordance with a unique declarative statement 4 to the effect that the combination of items of parent-descendant records in a network type data base 10 becomes unique in the network type data base 10. Unique declaration module 11 adds columns corresponding to the items designated in the unique declarative statement 4 to the applicable table definitions in the relational schema 6, and adds the contents of the unique declarative statement 4 as unique definition information. SQL statement translating module 2, when translating an SQL statement 7, according to the unique definition information in the relational schema 6, interprets it as an access to set a table combination, and generates a DML object designating an access route.
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