The subject of this thesis is the incorporation of temporal semantics into database rules and how the resultant syntax might be reconciled with the evolving SQL standard. In particular, it explores time-driven rules and the time-relationship between triggering events and associated actions. A review of the key research results in the area of database rules and the syntax developed for the major prototype implementations is conducted, and a working syntax , free of any limitations within the SQL standard, developed. Next, an operational definition is evolved through the application of this working syntax to two sample domains rich in 'temporal rules'. In each case a graphical representation of the domain is presented using an adapted object-oriented modelling technique followed by a mapping into the working temporal syntax. Attention is then turned to the SQL-92 standard and its future successor SQL3. An assessment is made of their implications for the working syntax developed in the earlier chapters - with particular reference to the specification of time and the use of database triggers. When an attempt was made to re-cast the working syntax into SQL, a satisfactory mapping, which succeeded in preserving the semantics of the original, could not be achieved. Support for time-based triggers; cyclic operations; delayed actions and rule lifetimes necessitated the development of appropriate modifications to the basic SQL3 draft syntax. The proposed extensions capture all of the semantics required for the specification of time-based rules. The example applications indicated that an extended SQLcompliant language approach allied to a sound objectoriented modelling formalism had a broad applicability. Furthermore, it was apparent that the addition of a temporal dimension to rule actions was a key enabling factor in increasing their semantic power.