III. Query builder, Joining Data
Once you have added the GIS data layers, the next step is to locate the data you need for safety analysis using queries. Queries are the primary mechanism for retrieving information from a database and consist of questions presented to the database in a predefined format. Queries are like equations (statements) that will provide the desired output. Queries can also check the validity of a statement. You will also learn how to create additional data by joining two existing datasets. The following steps will guide you through this process.