1. A system for unifying data, comprising: one or more computers; a plurality of separate data sources, each data source having a respective data access mechanism for facilitating querying thereof, each data source having stored thereon data for a particular clinical trials patient, and the plurality of data sources comprising (a) an electronic data capture (“EDC”) data source having EDC study data stored thereon, including EDC study data for the particular clinical trials patient, and (b) a patient diary data source having patient diary data stored thereon, including patient diary data for the particular clinical trials patient; a plurality of data source query function calls, each query function call querying a single data source, and each query function call using the data access mechanism of the single data source to facilitate access to the single data source; a first complex query calling a plurality of the data source query function calls, including, in response to a user query about the particular clinical trials patient, calling a query of the EDC data source for EDC study data for the particular clinical trials patient and a query of the patient diary data source for patient diary data for the particular clinical trials patient; wherein the first complex query does not identify any data source to query; wherein, in response to the first complex query, EDC study data for the particular clinical trials patient is retrieved from the EDC data source and patient diary data for the particular clinical trials patient is retrieved from the patient diary data source to populate at least one result set; a second complex query, in response to a user passing dimension instance parameters in the form of a list of a plurality of clinical trials patients, calls a first query of a first data source for patient characteristics data for a first clinical trials patient, calls a second query of a second data source for patient characteristics data for a second clinical trials patient, and calls a third query of a third data source for patient characteristics data for a third clinical trials patient; wherein the second complex query does not identify any data source to query; and wherein, in response to the second complex query, patient characteristics data for the first clinical trials patient is retrieved from the first data source, patient characteristics data for the second clinical trials patient is retrieved from the second data source, and patient characteristics data for the third clinical trials patient is retrieved from the third data source to populate at least one result set.