Uncertain data can be categorized as imprecise data and probabilistic data. In each of these categories, the uncertainty can be found at different granularity levels. Conventional data models are developed for the purpose of storing, manipulating and retrieving certain data. These data models do not extend their support for the management of uncertain data. Thus, a standalone data model is required aimed at storing, manipulating and retrieving certain as well as uncertain data. In this paper we introduce UDM-relations, an uncertain data model for the management of uncertain data along with certain data. Vertical partitioning approach is used to translate an uncertain relation into UDM-relations. Our data model supports ALU (Attribute-Level Uncertainty) as well as TLU (Tuple-Level Uncertainty) for the finite sets of possible worlds. It follows the concept of standard relational database technology. With slight modifications to standard relational algebra operators, we have introduced four relational operators that are used to evaluate a query on UDM-relations.