As the importance and utilization of multimedia data increase, we need to study representing and processing multimedia data within databases. To process multimedia data within databases, we need to precisely model multimedia data, to define data types and operations, and to make up query language supporting them. Therefore, in this paper, we modeled multimedia data using OMT so that we can support multimedia data within databases. We also propose an extended SQL, called MMSQl, which includes new types for supporting multimedia data types and efficiently make a query. Especially, MMSQL provides a mechanism to express temporal and spatial relationships which exist among objects in a multimedia data (internal) or among several multimedia data (external).