transaction time tables . 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 ... title TSQL2 Temporal Query Language Richard T. Snodgrass publisher SIGMOD accessdate April 28 ... and insights of TSQL2 into SQL3, termed SQL Temporal. Snodgrass initiated SQL Temporal part of the SQL3 ... 436 7. The TSQL2 Temporal Query Language, The TSQL2 Language Design Committee consisted of Richard ... TimeCenter http www.cs.arizona.edu rts tsql2.html TSQL2 Temporal Query Language Persondata ... more details
of the SQL standard ANSI X3.135. 1992 and ISO IEC 9075 1992 those extensions, known as TSQL2, were developed ... to that specification, changes were made to the language, and the definitive version of the TSQL2 ... tsql2.html title TSQL2 Temporal Query Language work www.cs.arizona.edu author Richard T. Snodgrass ... accessdate 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 ... and concepts described in the TSQL2 specification, such as Valid Time, Transaction Time and Bitemporal ... Model a treatment of the topic that includes many of the terms introduced by TSQL2 but also introduces ... versions of data in the same database. The latest version complies with TSQL2. http www.timeconsult.com .... It runs as a frontend to Oracle that accepts TSQL2 statements and generates SQL92 statements. http ... 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 different approach, see TSQL2 . ref name Snodgrass Richard T. Snodgrass Snodgrass, Richard T. http www.cs.arizona.edu rts tsql2.html TSQL2 Temporal Query Langu ... more details
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