QUERY COMPFILER WITH OPTIMIZED QUERY AND METHOD FOR OPTIMIZING QUERY

摘要

A method for optimizing query comprises the steps of searching a sub-query within a query of SQL; identifying a scalar sub-query from the searched sub-query; identifying a correlated scalar sub-query by analyzing the identified scalar sub-query; and unnesting a query having the identified correlated scalar sub-query in a new join form depending on the result form of the identified correlated scalar sub-query. [Reference numerals] (22) Searching a sub-query from a main query; (24) Identifying a scalar sub-query from the searched sub-query; (26) Identifying a correlated scalar sub-query from the scalar sub-query; (28) Result form; (AA) Start; (BB) Column; (CC) End