Front Page Applet ATSQL UC TUC SEQ NSEQ System Guidelines Requirements Doc Support Information Contribution Warranty Related Work Contact Future Work | ATSQL is a temporal database language that seamlessly extends SQL-92. The core concept of ATSQL are statement modifiers. They control the basic semantics of statements. We distinguish four classes of statements: upward compatibility (UC), temporal upward compatibility (TUC), sequentiality (SEQ), and nonsequentiality (NSEQ). The meaning of the statement modifiers naturally divides into four orthogonal parts, namely the specification of the statement class, the time-domain specification, the time-range specification, and the specification of coalescing. ATSQL respects user-specified intervals by default and provides a coalescing operation to support the point-based view. A detailed description of ATSQL is available in Seamless Integration of Time into SQL. ATSQL addresses advanced SQL features such as views, integrity constraints, assertions, the data definition language, aggregation and duplicates.