standard ANSI X3.135. 1992 and ISO IEC 9075 1992 those extensions, known as TSQL2, were developed ..., changes were made to the language, and the definitive version of the TSQL2 Language ... title TSQL2 Temporal Query Language work www.cs.arizona.edu author Richard T. Snodgrass authorlink ... 14 July 2009 ref An attempt was made to incorporate parts of TSQL2 into the new SQL standard SQL 1999 , called SQL3. Parts of TSQL2 were included in a new substandard of SQL3, ISO IEC 9075 7, called ... near the end of 2001. The ideas and concepts described in the TSQL2 specification, such as Valid ... introduced by TSQL2 but also introduces the Sixth normal form to solve some of the issues ... with TSQL2. http www.timeconsult.com Software Software.html TimeDB TimeDB is a free temporal relational DBMS by TimeConsult. It runs as a frontend to Oracle that accepts TSQL2 statements and generates ... more details
Databases, IEEE Computer 19 9 , September, 1986, pp. 35 42. ref TSQL2 , a temporal extension to the SQL 92 language standard, was designed by the TSQL2 committee, which was formed in July, 1993. Snodgrass chaired the TSQL2 language design committee. ref cite web url http www.informatik.uni trier.de ley db books collections snodgrass95.html title TSQL2 Temporal Query Language Richard T. Snodgrass ... to transfer some of the constructs and insights of TSQL2 into SQL3, termed SQL Temporal. Snodgrass ..., Inc., San Francisco, July, 1999, 504 xxiii pages, ISBN 1 55860 436 7. The TSQL2 Temporal Query Language, The TSQL2 Language Design Committee consisted of Richard T. Snodgrass chair , Ilsoo Ahn, Gad Ariav ... rts tsql2.html TSQL2 Temporal Query Language Metadata see Wikipedia Persondata Persondata ... more details
Sixth normal form 6NF is a term in relational database theory, used in two different ways. 6NF C. Date s definition A book by Christopher J. Date and others on temporal database s, ref da da lo Date et al., 2003 ref defined sixth normal form as a Database normalization Normal forms normal form for databases based on an extension of the relational algebra. In this work, the relational operators, such as join , are generalized to support a natural treatment of interval data, such as sequences of dates or moments in time. ref da da lo op. cit. , chapter 9 Generalizing the relational operators ref Sixth normal form is then based on this generalized join, as follows blockquote A relvar R table is in sixth normal form abbreviated 6NF if and only if it satisfies no nontrivial join dependencies at all where, as before, a join dependency is trivial if and only if at least one of the projections possibly U projections involved is taken over the set of all attributes of the relvar table concerned. Date et al. ref da da lo op. cit. , section 10.4, p. 176 ref blockquote Any relation in 6NF is also in fifth normal form 5NF . Sixth normal form is intended to decompose relation variables to irreducible components. Though this may be relatively unimportant for non temporal relation variables, it can be important when dealing with temporal variables or other interval data. For instance, if a relation comprises a supplier s name, status, and city, we may also want to add temporal data, such as the time during which these values are, or were, valid e.g., for historical data but the three values may vary independently of each other and at different rates. We may, for instance, wish to trace the history of changes to Status. For further discussion on Temporal Aggregation in SQL, see also Zimanyi. ref zimanyi Zimanyi 2005 ref For a non relational approach, see TSQL2 . ref name Snodgrass Richard T. Snodgrass Snodgrass, Richard T. http www.cs.arizona.edu rts tsql2.html TSQL2 Temporal Query ... more details
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