caa a22 4500 465820956 CHVBK 20180323112135.0 cr unu---uuuuu 170327e19900301xx s 000 0 eng 10.1007/BF01932129 doi (NATIONALLICENCE)springer-10.1007/BF01932129 Lossless outer joins with incomplete information [Elektronische Daten] [Sushil Jajodia, Frederick Springsteel] In the relational model of data, Rissanen's Theorem provides the basis for the usual normalization process based on decomposition of relations. However, many difficulties occur if information is incomplete in databases and nulls are required to represent missing or unknown data. We concentrate here on the notion of outer join and find some reasonable conditions to guarantee that outer join will also preserve the lossless join property for two relations. Next we provide a generalization of this result to several relations. BIT Foundations, 1990 Jajodia Sushil Department of Information Systems and Systems Engineering, George Mason University, 22030-4444, Fairfax, VA, USA aut Springsteel Frederick Department of Information Systems and Systems Engineering, George Mason University, 22030-4444, Fairfax, VA, USA aut BIT Numerical Mathematics Kluwer Academic Publishers 30/1(1990-03-01), 34-41 0006-3835 30:1<34 1990 30 10543 https://doi.org/10.1007/BF01932129 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF01932129 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Jajodia Sushil Department of Information Systems and Systems Engineering, George Mason University, 22030-4444, Fairfax, VA, USA aut NATIONALLICENCE 700 1- Springsteel Frederick Department of Information Systems and Systems Engineering, George Mason University, 22030-4444, Fairfax, VA, USA aut NATIONALLICENCE 773 0- BIT Numerical Mathematics Kluwer Academic Publishers 30/1(1990-03-01), 34-41 0006-3835 30:1<34 1990 30 10543 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer