Queries on one relation

Appendix C - Other relational languages, first presents the relational query language Query-by-Example (QBE), which was designed to be used by non-programmers. In QBE, queries look like a collection of tables containing an example of data to be retrieved. The graphical query language of Microsoft Access, which is based on QBE, is presented next, followed by the Datalog language, which has a syntax modeled after the logic-programming language Prolog.

61p haojiubujain04 27-07-2023 13 5   Download

This paper introduces a probabilistic relational database model, called PRDB, for representing and querying uncertain information of objects in practice. To develop the PRDB model, first, we represent the relational attribute value as a pair of probabilistic distributions on a set for modeling the possibility that the attribute can take one of the values of the set with a probability belonging to the interval which is inferred from the pair of probabilistic distributions

17p dieutringuyen 07-06-2017 34 1   Download

preconstructed dictionaries or thesauruses. Even in this relatively simplified environment one does not normally undertake a linguistic analysis of any scope. In fact, syntactic and semantic analysis have been used in b i b l i o g r a p h i c information retrieval only under special circumstances to analyze query phrases [22], to process structured text samples of a certain kind, [7,15], or finally to process texts in severely restricted topic areas. [2] Where s p e c i a l conditions do n o t o b t a i n , the preferred approach in...

7p buncha_1 08-05-2013 50 1   Download

One of the important observations done during the CLEF 2009 campaign (Ferro and Peters, 2009) related to CLIR was that the usage of Statistical Machine Translation (SMT) systems (eg. Google Translate) for query translation led to important improvements in the cross-lingual retrieval performance (the best CLIR performance increased from ˜55% of the monolingual baseline in 2008 to more than 90% in 2009 for French and German target languages). However, generalpurpose SMT systems are not necessarily adapted for query translation.

11p bunthai_1 06-05-2013 36 2   Download

One of the major challenges in TRECstyle question-answering (QA) is to overcome the mismatch in the lexical representations in the query space and document space. This is particularly severe in QA as exact answers, rather than documents, are required in response to questions. Most current approaches overcome the mismatch problem by employing either data redundancy strategy through the use of Web or linguistic resources. This paper investigates the integration of lexical relations and Web knowledge to tackle this problem.

8p bunthai_1 06-05-2013 49 1   Download

Finally, the HPDD sheds light on one of the leading issues of the day: the relationship between debt and growth. Separating countries into fast-, medium-, or slow–paced growers over 1885–2009, we find an intuitive pattern. 15 Fast growers consistently registered low debt ratios, while slow growers carried the highest debts for much of the sample period (Figure 7, upper panel). Further light is shed on the debt-growth relationship by a bubble chart that compares debt ratios and (total) PPP GDP (Figure 7, lower panel).

12p yasuyidol 02-04-2013 65 4   Download

Protein family databases obtain sequences fromone of the large protein sequence databases,most commonly SWISS- PROT with TrEMBL (Bairoch and Apweiler, 2000) but also PIR (Barker et al., 2000). They then apply an algorithm, either manual or automatic, to group the sequences into families. Each family is represented in one or more ways to facilitate both inspection by humans and comparison by computer programs. The most common representation is a multiple alignment of the family’s sequences, either with insertion and deletion (gap) characters or without.

12p yasuyidol 02-04-2013 46 6   Download

SQL, or structured query language, is the international standard language for creating and maintaining relational databases. It is the basis of all major databases in use today and is essential for the storage and retrieval of database information. This fun and friendly guide takes SQL and all its related topics and breaks it down into easily digestible pieces for you to understand. You’ll get the goods on relational database design, development, and maintenance, enabling you to start working with SQL right away!...

748p hoa_can 26-01-2013 74 18   Download