== i2b2 Ontology and CRC Discussion: 1 == Questions asked and points to ponder. Access to the demo database is useful here... === Ontology Cell tables compared to CRC concept_dimension table === There are three ontology tables within the demo Ontology cell: birn, i2b2 and custom_meta.[[br]] When I do a select count(*) from where c_visualattributes like '%LA%' I get the following figures: * birn: 37 * custom_meta: 0 * i2b2: 93807 When I do a "select count(*) from concept_dimension" within the CRC cell I get a count of 73590.[[br]] The totals are 93844 as opposed to 73590. Why is there a difference and what does it mean? === In an Ontology table, what does c_columndatatype really mean? === The docs state: "either ‘T’ for text or ‘N’ for numeric and describes the datatype of the concept". Yet the length of the column is varchar 50.[[br]] Within the demo project: * select count(*) from i2b2 where c_columndatatype like '%N%' ===> returns 0 * select count(*) from i2b2 where c_columndatatype like '%T%' ===> returns 134762 * select count(*) from i2b2 ===> returns 134762 Yet within the query tool (from the Workbench) I can select terms from a Labtest and constrain by value. This is undoubtedly possible because of the optional metadataxml column. But even so, what '''''does''''' c_columndatatype really mean?