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Mastering  QGIS
Mastering  QGIS

Mastering QGIS: Go beyond the basics and unleash the full power of QGIS with practical, step-by-step examples , Second Edition

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Profile Icon Corti Profile Icon Kurt Menke, GISP Profile Icon Van Hoesen, GISP Profile Icon Pirelli Profile Icon Smith Jr., GISP +1 more Show less
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Full star icon Full star icon Full star icon Full star icon Half star icon 4.5 (4 Ratings)
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Profile Icon Corti Profile Icon Kurt Menke, GISP Profile Icon Van Hoesen, GISP Profile Icon Pirelli Profile Icon Smith Jr., GISP +1 more Show less
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Mastering QGIS

Chapter 2. Creating Spatial Databases

This chapter covers the creation and editing of spatial databases using QGIS. The core concepts of databases will be briefly reviewed; however, we have assumed that you are generally familiar with database concepts and SQL for most of the content covered in this chapter. The topics that we will cover in this chapter are as follows:

  • Core concepts of database construction
  • Creating spatial databases
  • Importing and exporting data
  • Editing databases
  • Creating queries
  • Creating views

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...

Creating a spatial database

Creating a spatial database in QGIS is a simple operation. QGIS supports PostGIS, SpatiaLite, MSSQL, SQL Anywhere, and Oracle Spatial databases. We will cover SpatiaLite, an open source project that is cross-platform, simple, and lightweight, and provides quite a bit of functionality. SpatiaLite is a spatial database management system (DBMS) built on top of SQLite, a lightweight personal DBMS.

Note

SpatiaLite (and thus, SQLite) is built on a single-user architecture, which makes installation and management virtually nonexistent. The trade-off, however, is that it neither does a good job of supporting multiple concurrent connections, nor does it support a client-server architecture. For a more complex DBMS, PostGIS is an excellent open source option.

We will create a new SpatiaLite database that we will use for the remaining exercises in this chapter; to do this, perform the following steps:

  1. Open QGIS Desktop and open the Browser panel. If the Browser panel is missing...

Importing data into a SpatiaLite database

Importing data into a SpatiaLite database is easy using the DB Manager. SpatiaLite supports the following commonly-used formats, as well as many other formats, for importing files:

  • Shapefile (.shp)
  • dBase (.dbf)
  • Text (.txt), Commas Separate Values (.csv), and Excel spreadsheets (.xls/.xlsx)
  • AutoCAD DXF (.dxf)
  • Geography Markup Language (.gml)
  • Keyhole Markup Language (.kml)
  • Geometry JavaScript Object Notation (.geojson)
  • Scalable Vector Graphics (.svg)

Let's use DB Manager to import data in a few different formats into our GiffordPinochet.sqlite database.

Importing KML into SpatiaLite

To import a KML file into a SpatiaLite database, complete the following steps:

  1. Open DB Manager by clicking on DB Manager under Database. Expand SpatiaLite and select GiffordPinochet.sqlite on the Tree panel.
  2. Navigate to Table | Import layer/file to open the Import vector layer dialog.
  3. Click on the ellipsis button at the right-hand side of the Input drop-down box. Choose Keyhole...

Exporting tables out of SpatiaLite

You can export tables from SpatiaLite to many different formats using DB Manager. Tables can be exported to the following commonly-used formats, as well as many other formats:

  • ESRI Shapefile (.shp)
  • dBase (.dbf)
  • Text (.txt), Commas Separate Values (.csv), and Excel spreadsheets (.xls/.xlsx)
  • AutoCAD DXF (.dxf)
  • Geography Markup Language (.gml)
  • Keyhole Markup Language (.kml)
  • Geometry JavaScript Object Notation (.geojson)
  • GeoRSS (.xml)

To demonstrate an export, export the Waterfalls table to the shapefile format by performing the following steps:

  1. Open DB Manager by clicking on DB Manager under Database. Expand SpatiaLite and select the database from which you wish to export a table in the Tree panel.
  2. In the Tree panel, select the table that you wish to export.
  3. Navigate to Table | Export to file to open the Export to vector file dialog.
  4. In the Format dropdown box, choose ESRI Shapefile.
  5. Click on the ellipsis button at the right-hand side of the Output file text box and name...

Managing tables

DB Manager provides functions to create, rename, edit, delete, and empty tables using tools found under the Table menu. In this section, we will discuss each tool.

Creating a new table

Creating new tables using DB Manager is fairly straightforward. When creating a new table, you can specify whether it will be a spatial table or a nonspatial table. In this section, we will create a new spatial table in SpatiaLite to hold data about mountain peaks in a park; to do this, perform the following steps:

Tip

To quickly create a new SpatiaLite layer (and optionally a database) in one dialog box in QGIS Desktop, navigate to Layer | Create Layer | New SpatiaLite Layer….

  1. Open DB Manager by clicking on DB Manager under Database. Expand SpatiaLite and select GiffordPinochet.sqlite in the Tree panel.
  2. Navigate to Table | Create Table to open the Create Table window.
  3. Enter Peaks as the table name.
  4. Click on the Add field button to add a new table field. A new row will appear in the field list...

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...

Creating a spatial database


Creating a spatial database in QGIS is a simple operation. QGIS supports PostGIS, SpatiaLite, MSSQL, SQL Anywhere, and Oracle Spatial databases. We will cover SpatiaLite, an open source project that is cross-platform, simple, and lightweight, and provides quite a bit of functionality. SpatiaLite is a spatial database management system (DBMS) built on top of SQLite, a lightweight personal DBMS.

Note

SpatiaLite (and thus, SQLite) is built on a single-user architecture, which makes installation and management virtually nonexistent. The trade-off, however, is that it neither does a good job of supporting multiple concurrent connections, nor does it support a client-server architecture. For a more complex DBMS, PostGIS is an excellent open source option.

We will create a new SpatiaLite database that we will use for the remaining exercises in this chapter; to do this, perform the following steps:

  1. Open QGIS Desktop and open the Browser panel. If the Browser panel is missing...

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Key benefits

  • •This book is your one-stop solution to all of your GIS needs using the open source QGIS
  • •Master QGIS by learning about database integration, geoprocessing tools, Python scripts, advanced cartography, and custom plugins
  • •This example-rich, practical guide will help you create sophisticated analyses and maps

Description

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.

Who is this book for?

If you are a GIS professional, a consultant, a student, or perhaps a fast learner who wants to go beyond the basics of QGIS, then this book is for you. It will prepare you to realize the full potential of QGIS.

What you will learn

  • • Create and manage a spatial database
  • • Get to know advanced techniques to style GIS data
  • • Prepare both vector and raster data for processing
  • • Add heat maps, live layer effects, and labels to your maps
  • • Master LAStools and GRASS integration with the Processing Toolbox
  • • Edit and repair topological data errors
  • • Automate workflows with batch processing and the QGIS Graphical Modeler
  • • Integrate Python scripting into your data processing workflows
  • • Develop your own QGIS plugin

Product Details

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Publication date : Sep 30, 2016
Length: 486 pages
Edition : 2nd
Language : English
ISBN-13 : 9781786460370
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Length: 486 pages
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Language : English
ISBN-13 : 9781786460370
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Table of Contents

12 Chapters
1. A Refreshing Look at QGIS Chevron down icon Chevron up icon
2. Creating Spatial Databases Chevron down icon Chevron up icon
3. Styling Raster and Vector Data Chevron down icon Chevron up icon
4. Preparing Vector Data for Processing Chevron down icon Chevron up icon
5. Preparing Raster Data for Processing Chevron down icon Chevron up icon
6. Advanced Data Creation and Editing Chevron down icon Chevron up icon
7. Advanced Data Visualization Chevron down icon Chevron up icon
8. The Processing Toolbox Chevron down icon Chevron up icon
9. Automating Workflows with the Graphical Modeler Chevron down icon Chevron up icon
10. Creating QGIS Plugins with PyQGIS and Problem Solving Chevron down icon Chevron up icon
11. PyQGIS Scripting Chevron down icon Chevron up icon
Index Chevron down icon Chevron up icon

Customer reviews

Rating distribution
Full star icon Full star icon Full star icon Full star icon Half star icon 4.5
(4 Ratings)
5 star 50%
4 star 50%
3 star 0%
2 star 0%
1 star 0%
Maya Aug 04, 2017
Full star icon Full star icon Full star icon Full star icon Full star icon 5
good book to learn gis
Amazon Verified review Amazon
RAFAEL VÁZQUEZ MÁRQUEZ Nov 03, 2017
Full star icon Full star icon Full star icon Full star icon Full star icon 5
A pesar de que es un libro de nivel intermedio, trae un capitulo breve de introducción, los capitulos estan muy bien explicados.
Amazon Verified review Amazon
Grumpy Jun 22, 2019
Full star icon Full star icon Full star icon Full star icon Empty star icon 4
Mine said for sale in India on the cover, but it's a decent intro to qgis
Amazon Verified review Amazon
Lance Case Sep 18, 2017
Full star icon Full star icon Full star icon Full star icon Empty star icon 4
Highly recommend this for anyone serious about learning how to use QGIS. Online tutorials and user forums will only get you so far. This book steps through most, if not all, of the features of the application. It's perfect for a general introduction to the software and provides a nice starting point for your specific application. My only complaint is that the printed book is in black & white with an option to download color pictures from the publisher. The PDF version is in full color. I like having a physical book for reference, but some of the graphic examples don't work in black & white.
Amazon Verified review Amazon
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