Toward a multilevel relational data language

An implementation-dependent multilevel query language called MSQL (multilevel structured query language) for defining and manipulating (multilevel relations) is defined. The MSQL language includes an access class data type, integrity constraints, primary keys, and provision for specification of classification domains for attributes of multilevel relations. The near-term SeaView design includes an MSQL preprocessor that translates MSQL queries into a set of standard SQL queries on the single-level base relations.<
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