1. A method for transferring data from a database into a hierarchical structure, the method comprising: accepting a tagging tree for processing, the tagging tree comprising a plurality of nodes, each node within the plurality of nodes being one of a tagging node, an execution node and a data node, the tagging tree comprising: at least one tagging node that each specifies a field in a hierarchical structure, a plurality of execution nodes that each specifies a database query command for at least one data object, and at least one data node that each specifies a binding between each of the at least one data object specified by a respective execution node within the plurality of execution nodes and at least one field specified in the at least one tagging node; combining, into a single database query, database query commands from at least two of the plurality of execution nodes that each specifies a same data source; executing the single database query to retrieve a set of data objects; and placing, based upon a respective binding in the at least one data node, at least one data object within the set of data objects into at least one field of a plurality of fields to create an output having a composite hierarchical structure; creating a set of reduced query trees, wherein the set of reduced query trees comprise the plurality of execution nodes with the at least two of the plurality of execution nodes that were combined into the single database query removed; combining at least an additional two of the plurality of execution nodes within the set of reduced query trees into at least one additional single database query, wherein each of the at least additional two of the plurality of execution nodes specifies a second data source; and executing the additional single database query to retrieve an additional set of data objects, wherein the placing at least one data object further comprises placing at least one data object within the additional set of data objects into at least an additional one field of the plurality of fields based upon bindings specified by the at least one data node.
1. A method for transferring data from a database into a hierarchical structure, the method comprising: accepting a tagging tree for processing, the tagging tree comprising a plurality of nodes, each node within the plurality of nodes being one of a tagging node, an execution node and a data node, the tagging tree comprising: at least one tagging node that each specifies a field in a hierarchical structure, a plurality of execution nodes that each specifies a database query command for at least one data object, and at least one data node that each specifies a binding between each of the at least one data object specified by a respective execution node within the plurality of execution nodes and at least one field specified in the at least one tagging node; combining, into a single database query, database query commands from at least two of the plurality of execution nodes that each specifies a same data source; executing the single database query to retrieve a set of data objects; and placing, based upon a respective binding in the at least one data node, at least one data object within the set of data objects into at least one field of a plurality of fields to create an output having a composite hierarchical structure; creating a set of reduced query trees, wherein the set of reduced query trees comprise the plurality of execution nodes with the at least two of the plurality of execution nodes that were combined into the single database query removed; combining at least an additional two of the plurality of execution nodes within the set of reduced query trees into at least one additional single database query, wherein each of the at least additional two of the plurality of execution nodes specifies a second data source; and executing the additional single database query to retrieve an additional set of data objects, wherein the placing at least one data object further comprises placing at least one data object within the additional set of data objects into at least an additional one field of the plurality of fields based upon bindings specified by the at least one data node. 2. The method according to claim 1 , wherein the single database query comprises an outer-union SQL query.