Spatial SQL with Postgres : A language for geographers

This lecture will walk you through installing PostGRES, PostGIS, and QGIS so that you can begin learning how to use SQL.

In this lecture, I will step you through loading the course data, which includes a Postgres dump file for a small city in upstate New York.  

In this lecture I will review what SQL is, and demonstrate some of the powerful features of SQL and spatial SQL.  This lecture will set the stage for why you'll want to be using SQL in your career.

Before we get down to the nitty-gritty of this course, I want to quickly show you just how powerful SQL is within a GIS and spatial context.  If this doesn't convince you to start using SQL, nothing will.  

Also, all of these quick examples use the course data, so you can stop the video and begin typing the SQL code alongside of me. 

In this lecture we will dive into looking at how SQL handles different numeric, boolean, and text data types.  Within the context of our city-wide GIS, we'll work together to type in SQL commands that demonstrate the special functions for numeric, boolean, and text data.

In this lecture we will dive into looking at how SQL handles different Date, Time, and spatial data types.  Within the context of our city-wide GIS, we'll work together to type in SQL commands that demonstrate the special functions for data, time, and spatial data.

In this lecture, we'll explore the traditional SQL commands of SELECT, WHERE and GROUP BY -  along with many conditional expressions.  You'll learn the basic syntax, and then we'll gradually add more functionality to show you how to issue advanced queries.  Don't be intimidated, I'll be working right-along side of you.  This stuff builds on itself so well, you won't believe what you'll start accomplishing by the end of the lecture.

There simply isn't enough time to show you all the cool things you can do with GROUP BY.  So, we had to create another lecture just to fit more of it in.  We are going to be doing some really sophisticated stuff, but you'd never know it, since we are simply building off of what we just learned.  

You can create conditional CASE statements in SQL just like any other programming language.  In this video I will show you how to create CASE statements for numeric, text, and spatial data.

In this lecture you will look at all kinds of different aggregate functions in SQL, and even perform statistical analysis and geographic analysis with the functions.  Don't worry, we'll go slow, and like everything else, we'll step into it one command at a time.

This lecture is packed with a potpourri of SQL commands, and like everything else, we'll start of slow and easy, and as we progressively add more complexity, you'll see how easy it is to create a very sophisticated query - try doing this in a traditional GIS or spreadsheet!

SQL is not just a query language.  It allows you to also change things: add tables, delete tables, change tables, update individual records, bulk load records, add records from one table to another table, you get the idea!  In this lecture I will walk you through the basic ways to change data in a table.  And, just for fun, we'll even change geometry within a table.

SQL functions work just like functions in other programming languages.  You create a function and then pass data to the function to return values.  In this section I will step you through how to create functions with SQL.

Geographic analysis can work with multiple representations and coordinate system - the trick is, you have to define them correctly or the software won't have a clue as to where the data is located.  This lecture will show you how to define and change coordinate systems.

Get ready to start writing spatial operations with SQL.  We'll build on all those previous SQL functions and will add spatial operations like adjacency, buffering, intersection, distance calculation, and more.  You'll be amazed at how you can expand basic spatial operations into complex spatial queries using the GROUP BY, UNION, and other SQL operations.  And the best part is, it's easy, because it's just SQL!  

One of the real meat-and-potato functionality of GIS is the ability to perform topological overlay functions.  When you think about it, they are all based on the same kinds of functionality of finding areas that intersect or areas that don't intersect, or both.  This obviously lends itself to SQL really nicely, as we can solve one part of the puzzle at a time.  In this lecture you'll learn how to perform classic topological overlay functions of ERASE, INTERSECT, and IDENTITY.

Get ready to create a geographic model.  In this lecture we will once again start out small, and then progressively add more complexity to create distance, adjacency, and interaction models that are typically used in geographic analysis.

In this lecture I'm going to show you how to create a spatial operation that performs a statistical analysis for evaluating spatial randomness, clustering, and dispersion.  You'll see how creating an analytical tool like the nearest neighbor index (NNI) is a simple matter of adding a few SQL operations like GROUP BY and ORDER to a basic SQL distance operation.