Book Image

Mastering QGIS - Second Edition

By : Kurt Menke, GISP, Paolo Corti, Richard Smith Jr., GISP, Luigi Pirelli, John Van Hoesen, GISP
Book Image

Mastering QGIS - Second Edition

By: Kurt Menke, GISP, Paolo Corti, Richard Smith Jr., GISP, Luigi Pirelli, John Van Hoesen, GISP

Overview of this book

QGIS is an open source solution to GIS. It is widely used by GIS professionals all over the world. It is the leading alternative to the proprietary GIS software. Although QGIS is described as intuitive, it is also by default complex. Knowing which tools to use and how to apply them is essential to producing valuable deliverables on time. Starting with a refresher on the QGIS basics, this book will take you all the way through to creating your first custom QGIS plugin. From the refresher, we will recap how to create, populate, and manage a spatial database. You’ll also walk through styling GIS data, from creating custom symbols and color ramps to using blending modes. In the next section, you will discover how to prepare vector, heat maps, and create live layer effects, labeling, and raster data for processing. You’ll also discover advanced data creation and editing techniques. The last third of the book covers the more technical aspects of QGIS such as using LAStools and GRASS GIS’s integration with the Processing Toolbox, how to automate workflows with batch processing, and how to create graphical models. Finally, you will see how to create and run Python data processing scripts and write your own QGIS plugin with pyqgis. By the end of the book, you will understand how to work with all the aspects of QGIS, and will be ready to use it for any type of GIS work.
Table of Contents (19 chapters)
Mastering QGIS - Second Edition
Credits
Foreword
About the Authors
About the Reviewer
www.PacktPub.com
Preface
Index

Fundamental database concepts


A database is a structured collection of data. Databases provide multiple benefits over data stored in a flat file format, such as a shapefile or KML. These benefits include complex queries, complex relationships, scalability, security, data integrity, and transactions, to name a few. Using databases to store geospatial data is relatively easy, considering the aforementioned benefits.

Note

There are multiple types of database; however, the most common type of database, and the type of database that this chapter will cover, is the relational database.

Describing database tables

A relational database stores data in tables. A table is composed of rows and columns, where each row is a single data record and each column stores a field value associated with each record. A table can have any number of records; however, each field is uniquely named and stores a specific type of data.

A data type restricts the information that can be stored in a field, and it is very important...