000 02921nam a22005175i 4500
001 978-3-540-46507-2
003 DE-He213
005 20160624102015.0
007 cr nn 008mamaa
008 121227s1991 gw | s |||| 0|eng d
020 _a9783540465072
_9978-3-540-46507-2
024 7 _a10.1007/3-540-54919-6
_2doi
050 4 _aQA76.9.D3
072 7 _aUN
_2bicssc
072 7 _aUMT
_2bicssc
072 7 _aCOM021000
_2bisacsh
082 0 4 _a005.74
_223
245 1 4 _aThe Problem of Incomplete Information in Relational Databases
_h[electronic resource] /
_cedited by Gösta Grahne.
260 1 _aBerlin, Heidelberg :
_bSpringer Berlin Heidelberg,
_c1991.
264 1 _aBerlin, Heidelberg :
_bSpringer Berlin Heidelberg,
_c1991.
300 _aVIII, 164 p.
_bonline resource.
336 _atext
_btxt
_2rdacontent
337 _acomputer
_bc
_2rdamedia
338 _aonline resource
_bcr
_2rdacarrier
347 _atext file
_bPDF
_2rda
490 1 _aLecture Notes in Computer Science,
_x0302-9743 ;
_v554
505 0 _aRelational databases -- Semantic aspects of incomplete information -- Syntactic and algorithmic aspects of incomplete information -- Computational complexity aspects of incomplete information -- Some conclusive aspects.
520 _aIn a relational database the information is recorded as rows in tables. However, in many practical situations the available information is incomplete and the values for some columns are missing. Yet few existing database management systems allow the user to enter null values in the database. This monograph analyses the problems raised by allowing null values in relational databases. The analysis covers semantical, syntactical, and computational aspects. Algorithms for query evaluation, dependency enforcement and updates in the presence of null values are also given. The analysis of the computational complexity of the algorithms suggests that from a practical point of view the database should be stored as Horn tables, which are generalizations of ordinary relations, allowing null values and Horn clause-like restrictions on these null values. Horn tables efficiently support a large class of queries, dependencies and updates.
650 0 _aComputer science.
650 0 _aComputer software.
650 0 _aDatabase management.
650 0 _aArtificial intelligence.
650 1 4 _aComputer Science.
650 2 4 _aDatabase Management.
650 2 4 _aAlgorithm Analysis and Problem Complexity.
650 2 4 _aArtificial Intelligence (incl. Robotics).
700 1 _aGrahne, Gösta.
_eeditor.
710 2 _aSpringerLink (Online service)
773 0 _tSpringer eBooks
776 0 8 _iPrinted edition:
_z9783540549192
786 _dSpringer
830 0 _aLecture Notes in Computer Science,
_x0302-9743 ;
_v554
856 4 0 _uhttp://dx.doi.org/10.1007/3-540-54919-6
942 _2EBK5808
_cEBK
999 _c35102
_d35102