Duro is a relational database library.
- Tuples and tables (relvars).
- Relational algebra: RENAME, select (restrict), project, EXTEND, JOIN, SEMIJOIN, UNION, INTERSECT, MINUS, SEMIMINUS, 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.
- Declarative integrity.
- Tcl interface, including support for relational expressions in Tutorial D syntax and operators implemented in Tcl ("stored procedures").
- Simple GUI admin tool.
- Berkeley DB database library