Object oriented query path expression to relational outer join translator method, system, article of manufacture, and computer program product

摘要

A path expression is translated to a relational database outer join by analyzing each path expression defined in each level of the object oriented query, and by identifying each path expression which can be a candidate for a translation to an outer join. The path expressions are ordered staffing with path expressions defined in a FROM clause. These ordered path expressions are grouped sequentially based upon on a source-target dependency between ordered path expressions and based upon the identifications as a candidate for a translation to an outer join. A quantifier is created for each path expression, said quantifier comprising a variable representing a table in a relational database, and each grouped path expression is replaced with a corresponding quantifier and related table in a relational database. A translation of the object oriented query to a relational query is then completed.