Logical data model of ExpressDB and its usage as a generalized two-dimensional table. (a) High level logical data model. Rectangles represent tables in the database and connecting lines represent database table relationships as described in the legend and as per Teorey (1994). (b) Use of Express DB as a generalized two-dimensional table. Database load files are usually in the form of tables with each line dedicated to an ORF or control probe and each column to a measurement, computed value, or descriptive field. The ExpressDB ORF table contains records for all ORFs or control used by any load file, and each measurement column from each load file is represented by a Measure record. Measure records associated with a related set of experiments, especially measures reported by a single literature reference, are all linked via a database relationship to a common Expression Data Set record, although multiple Expression Data Set records are used for some references. Measurement column values for each ORF for an experimental data series are given in Expression Data Point records that are linked to their ORF and Measure records via database relationships. To accommodate different formats of column values, five different Expression Data Point tables are available, each supporting a different format.
