Spatial Database Query – Since a GIS can be thought of as essentially being a large relational database, it is possible to relate or integrate different tables based on spatial characteristics and use the spatial statistics together with a database query to identify records meeting a criteria. For example, you would like to identify which male patients who visited a county clinic in the past 90 days reside within 2 miles of a county clinic. This can be accomplished in two steps:

The first step would be to identify the records which met the database query criteria (E.G. males who visited the clinic in the past 90 days).

2. The second step would involve selecting a subset of the first query by determining which patients live within a 2 mile radius of a clinic.

This would typically be accomplished by creating rings with a 2 mile radius surrounding each clinic and then determining which of the previously selected male patient cases are located within any of the rings.