1. A computer-implemented method for storing XML documents in a relational database, the method comprising: populating a first table and a second table with data from an XML document that conforms to an XML schema, wherein the document contains an occurrence of a root element type and an occurrence of a second element type that descends from the occurrence of a root element type; wherein the step of populating comprising: storing a record in the first table, wherein the record in the first table corresponds with at least the occurrence of the root element type; and storing a record in the second table, wherein the record in the second table corresponds with the occurrence of the second element type and includes a value that identifies the record in the first table; and wherein the first table is a separate table than the second table.