== i2b2 - DB Basics ==

This is a very bare basics. I'm only interested at present in the observation_fact table and its relationship with the concept_dimension table within the CRC Cell. And then the correspondence with any ontology tables within the Ontology Cell. 

{{{
+-------------CRC Cell-------------+   +-----------Ontology Cell---------+
|                                  |   |                                 |
|        +===================+     |   |     +=====================+     |
|        | concept_dimension |<<<=========>>>| an ontology table   |>:   | 
|        +=========^=========+     |   |     +==========^==========+ :   |
|                  |               |   |                |            :   |
|                  |               |   |                |            :   |
|                  |               |   |                |            :   |
|        +=========^=========+     |   |     +==========^==========+ :   |
|        | observation_fact  |     |   |     |   table_access      | :   | 
|        +===V===========V===+     |   |     +=====================+ :   |
|            |           |         |   |                             :   |
|            |           |         |   +-----------------------------:---+
| +==========V========+  |         |                                 :
| | patient_dimension |  |         |           +------------+        :
| +===================+  |         |<<<<<<<<<<<| QUERY TOOL |<<<<<<<<:
|                        |         |           +------------+  
|             +==========V======+  |
|             | visit_dimension |  |
|             +=================+  |
+----------------------------------+
}}}
There is a great deal more to it than the above suggests. It needs a deal of studying.[[BR]]
There can be a number of ontology tables within the Ontology Cell. We know which are ontology tables by an entry in the table_access table.