Query by example for nested tables

摘要

QBEN,a Query Example lanaguage for Neted tables,is described.QBEN is user-friendly and allows for the asy formulation of ocmplex queries.At hte same time,optimizaiton techniques can be incorportted that enable the global optimization of a series of queries.QBEN is addressed both to non-experts and experts.FCOmparison with other approaches is also made.