Book Image

Geospatial Analysis with SQL

By : Bonny P McClain
Book Image

Geospatial Analysis with SQL

By: Bonny P McClain

Overview of this book

Geospatial analysis is industry agnostic and a powerful tool for answering location questions. Combined with the power of SQL, developers and analysts worldwide rely on database integration to solve real-world spatial problems. This book introduces skills to help you detect and quantify patterns in datasets through data exploration, visualization, data engineering, and the application of analysis and spatial techniques. You will begin by exploring the fundamentals of geospatial analysis where you’ll learn about the importance of geospatial analysis and how location information enhances data exploration. Walter Tobler’s second law of geography states, “the phenomenon external to a geographic area of interest affects what goes on inside.” This quote will be the framework of the geospatial questions we will explore. You’ll then observe the framework of geospatial analysis using SQL while learning to create spatial databases and SQL queries and functions. By the end of this book, you will have an expanded toolbox of analytic skills such as PostGIS and QGIS to explore data questions and analysis of spatial information.
Table of Contents (13 chapters)
Free Chapter
Section 1: Getting Started with Geospatial Analytics
Section 2: SQL for Spatial Analytics

Differentiating polygons in OSM data

A reminder of the syntax used in SQL query language helps to clear our minds as we generate complex questions within and between datasets:

  • SELECT name_attribute: What is the attribute you are selecting from your dataset?
  • FROM name_table: What table are you selecting this attribute from?
  • WHERE: What conditions need to be met?
  • GROUP BY name_attribute: Should they be sorted by name, area, or ID for example?
  • HAVING: Additional criteria to be met, often a threshold value.

Try to recognize this template in queries you observe or create. There should be a story embedded in each query.

Spatial queries

How does PostGIS extract information from a database? Recall that we are querying coordinates, reference systems, and other dimensions from a wide variety of datasets of different geometries that include the length of a line, the area of a polygon, or even a point location. These are collected based on specific properties...