49 search results - page 1 / 10 » Some Properties of Query Languages for Bags |
DBPL
1993
Springer
13 years 8 months ago
1993
Springer
In this paper we study the expressive power of query languages for nested bags. We de ne the ambient bag language by generalizing the constructs of the relational language of Brea...
VLDB
1991
ACM
13 years 8 months ago
1991
ACM
We explore the implications of supporting bags (i.e. multisets) in a data model and associated query language, and present some formal results concerned with the algebraic propert...
ICDT
1997
ACM
13 years 8 months ago
1997
ACM
Abstract. The goal of this paper is to study tractable iteration mechanisms for bags. The presence of duplicates in bags prevents iteration mechanisms developed in the context of s...
SDB
1995
13 years 8 months ago
1995
Most of work on partial information in databases asks which operations of standard languages, like relational algebra, can still be performed correctly in the presence of nulls. In...
CORR
2011
Springer
12 years 8 months ago
2011
Springer
The annotation of the results of database transformations was shown to be very effective for various applications. Until recently, most works in this context focused on positive q...