00421nam a2200169Ia 4500008004100000020001500041041000800056082002400064100001900088245002200107260004000129300000800169365001100177650001300188650002600201650002400227140306s9999    xx            000 0 und d  a8170296447  aeng  a005.369 SQLbGRU/UN  aGruber, Martin  aUnderstanding SQL  aNew DelhibB P B Publicationsc1995  a484  bRs.225  aBooleans  aCorrelated subqueries  aRelational database