1. A computer-implemented method of outputting data, comprising: storing, by a computer system, first data in a first format, wherein the first format is one of a hierarchical format and a relational format; transforming, by the computer system, the first data from the first format to a second format, wherein the second format is neither the hierarchical format nor the relational format, wherein the second format is a source structure according to a unified data model, wherein the unified data model has a hierarchical structure with a plurality of tree nodes and a plurality of leaf nodes, and wherein a leaf node of the plurality of leaf nodes contains a table, wherein the table includes at least a portion of the first data; storing, by the computer system, the first data structured in the source structure; executing, by the computer system, a unified data model query on the first data having been transformed into the source structure, to result in second data structured in a target structure according to the unified data model, wherein executing the unified data model query comprises: creating the target structure as a second plurality of tree nodes and a second plurality of leaf nodes, wherein each of the second plurality of leaf nodes are repeatable, wherein each of the second plurality of tree nodes are not repeatable, and wherein the target structure differs from the source structure, computing a result of the unified data model query, wherein the result includes a second table that is based on at least a portion of the first data, and containing the second table in a second leaf node of the second plurality of leaf nodes, wherein the second leaf node differs from the leaf node that contains the table in the source structure; and outputting, by the computer system, the second data structured in the target structure.