TSQL2 Temporal Query Language

TSQL2 is a temporal extension to the SQL-92 language standard. The TSQL2 committee was formed in July, 1993 after a general invitation sent to the community. This committee consisted of Richard T. Snodgrass, Ilsoo Ahn, Gad Ariav, Don Batory, James Clifford, Curtis E. Dyreson, Christian S. Jensen, Ramez Elmasri, Fabio Grandi, Wolfgang Käfer, Nick Kline, Krishna Kulkarni, Ting Y. Cliff Leung, Nikos Lorentzos, John F. Roddick, Arie Segev, Michael D. Soo, and Surynarayana M. Sripada. The committee produced a preliminary language specification the following January, which appeared in the March 1994 ACM SIGMOD Record. Based on responses to that specification, changes were made to the language, and the definitive version of the TSQL2 Language Specification was published as a 71-page TSQL2 technical report in September, 1994 [dvi, ps, pdf]. The affiliations and e-mail addresses of the TSQL2 Language Design Committee members may be found in a separate section at the end of the language specification. A tutorial of this language appeared in the September 1994 ACM SIGMOD Record.

Associated with the language specification is a collection of commentaries which discuss design decisions, provide examples, and consider how the language may be implemented. These commentaries were originally proposals to the TSQL2 Language Design Committee. They now serve a different purpose: to provide examples of the constructs, motivate the many decisions made during the language design, and compare TSQL2 with the many other language proposals that have been made over the last twenty years. It should be emphasized that these commentaries are not part of the TSQL2 language specification per se, but rather supplement and elaborate upon it. The language specification proper is the final word on TSQL2.

The commentaries, along with the language specification, several indexes, and other supporting material, has been published as a book,

Richard T. Snodgrass, editor, Ilsoo Ahn, Gad Ariav, Don Batory, James Clifford, Curtis E. Dyreson, Ramez Elmasri, Fabio Grandi, Christian S. Jensen, Wolfgang Kaefer, Nick Kline, Krishna Kulkarni, T. Y. Cliff Leung, Nikos Lorentzos, John F. Roddick, Arie Segev, Michael D. Soo and Suryanarayana M. Sripada, The TSQL2 Temporal Query Language, Kluwer Academic Publishers, 1995, 674+xxiv pages.

This entire book appears on the SIGMOD Anthology DVD publication, available at SIGMOD.

The TSQL2 Language Specification as it appears in the TSQL2 book is also available [ps, pdf]. The .pdf files are Adobe PDF; the .ps files are postscript files.

The evaluation commentary appears in the book in an abbreviated form; the full commentary is available here [ps, pdf]. The file tl2tsql2.pl is a Prolog program that translates allowed temporal logic to TSQL2. This program was written by Michael Boehlen (boehlen@tina.inf.unibz.it). He may be contacted for a paper that describes this translation. This is a rather dated version of that program. Newer versions are available at the TimeCenter software page (specifically the TimeDB and Tiger systems).

The constructs and insights of TSQL2 have been proposed for incorporation into the SQL3 language.


In May 1992 Rick circulated a white paper that proposed that a temporal extention to SQL be produced by the research community.

On June 28, 1993 Rick send an email to the 46 attendees of the ARPA/NSF International Workshop on an Infratstructure for Temporal Databases (which was held June 14-16, 1993 in Arlington, Texas) proposing three separate efforts: (i) SQL2/3: to define an interval data type, (ii) TSQL2: to define a short-term temporal extension to SQL2, and (iii) TSQL3: to define a long-term temporal extension to SQL3. He offered to coordinate the TSQL2 effort and asked for volunteer coordinators for the other two groups.

On July 1, 1993 Rick sent an email to the same people outlining a structure for the design of TSQL2 and soliciting members. On July 5, 1993 Rick sent an email to the tsql mailing list proposing the three efforts and indicating the coordinators of each of those efforts, asking for volunteer members for each group. The extremely ambitious stated goal for the TSQL2 group was an initial design by August 23, 1993. On July 7, 1993 Rick sent an email to the initial seven members of the TSQL2 language design working group outlining the ground rules for the exercise. On July 14, 1993 Rick sent an email to the now ten members of the working group outlining his personal views on design aspects.

The group corresponded via electronic mail, submitting, debating, and refining proposals for the various portions of the language. In September, 1993 the first draft specification, accompanied by thirteen commentaries, was distributed to the committee. In December 1993 a much enlarged draft, accompanied by some twenty-four commentaries, was distributed to the committee. A preliminary language specification appeared in the March 1994 issue of ACM SIGMOD Record and twenty-three commentaries were made available via anonymous FTP. A tutorial of the language appeared in the September 1994 issue of ACM SIGMOD Record and the final language specification and 28 commentaries were also made available via anonymous FTP in early October 2004, less than fifteen months after the committee had been founded. The final specification and commentaries appeared in a 674-page book published by Kluwer Academic Publishers that was distributed at a temporal database workshop in summer of 1995.

Correspondence may be directed to the chair of the TSQL2 Language Design Committee, Richard T.Snodgrass, Department of Computer Science, University of Arizona, Tucson, AZ 85721, rts@cs.arizona.edu.