As you remember, GIS data consists of two major (almost non-separatable) components describing objects in space: spatial and attriute component. General datasets, available to you (your organization), can be massive. For purpose of analysis you will need a subset of data to work with, to run your analytical tools over, etc. In this section, we will give you an overview of the tools and methods used for selecting and summarizing such manageble subsets of "general data". You can do analysis of gis data in two major ways:

For example, doing some planning analysis, you can try to find all houses located closer than 1 mile to a railroad (spatial query) or to find all houses which were built in a specific year (attribute data query). So we will review the query components used to look at attribute data. To perform this task, we will work with attribute data using SQL language.