Duro is a relational open-source database library written in C http://duro.sourceforge.net/ . It is based on the principles laid down in the book Foundation for Future Database Systems: The Third Manifesto by C. J. Date and Hugh Darwen. 

The goal of the Duro project is to create a library which is as compliant with the proposed database language D as it is possible for a C library. This library is supposed to serve as a basis for a truly relational database management system (TRDBMS). 

Duro is published under the terms of the GNU General Public License. 

The current release of Duro is 0.9, released 2005-Mar-02. Some features: 

   * Tuples and tables (relvars). 
   * Relational algebra: RENAME, select (restrict), project, EXTEND, JOIN, UNION, INTERSECT, MINUS, SUMMARIZE PER, DIVIDEBY PER, WRAP, UNWRAP, GROUP, and UNGROUP. 
   * Virtual tables (views). 
   * Locking and nested transactions. 
   * Duro tables are true sets -- uniqueness of tuples (rows) is always enforced. When creating real tables, at least one candidate key must be supplied. A candidate key may be empty. 
   * User-defined types (including type constraints) and operators. 
   * Tcl interface, including support for relational expressions in Tutorial D syntax and operators implemented in Tcl ("stored procedures"). 
   * Simple GUI admin tool.
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''[escargo] 1 Aug 2005'' - This is just begging for confusion between the D programming Language[http://www.digitalmars.com/d/], viewed by its creators as a reengineering of [C] and C++, and this
other ''proposed database language D''[http://www.thethirdmanifesto.com/].  There are only so many letters
of the alphabet, and there are probably programming languages for each of them. (I seem to remember a couple
based on alternative pronunciations: Eh and Zed, both originating out of Canada, as I recall.)
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[Category Database]