This article will get you started with the basics of Gnosis Queries & Reporting. Queries in Gnosis - as in most other database systems - form the basis of much of the work performed by the system. Queries can provide you with information via reporting, or they can cause some other action to be performed with the results of the query - such as sending them all a communications item or requesting them to take some action.
The Anatomy of a Query
Let's imagine for a moment, that your Gnosis database is a house containing your data. You look at the data through the large front door and through windows in each room. The main door lets you see a broad selection of information through the house but does not let you see deeply into any particular room. Each window can see deeply into its room but only lets you see parts of the rest of the house.
These doors and windows are called "Schemas" in Gnosis parlance and the first thing you must do when getting data from your database house is decide through which opening (schema) you need to look. There's a good introductory article that gives examples of this here.
Once you have chosen a schema, you will need to build or choose the query you will use to get the data out of your system: