I have been reading a lot about PostGIS, but I am struggling to find a good beginner's guide.
Which tutorials/books do you recommend?
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Boundless (formerly opengeo) has a very very good workshop with a lot of exercises on the PostGIS database. I would start with this one.
Some starting points to consider:
Also, for general introduction to PostgreSQL I quite enjoyed 'Beginning Databases with PostreSQL' book by Matthew & Stones.
My way to find PostGIS was http://bostongis.org/?content_name=postgis_tut01#20
there is three parts of the tutorial. I really like it.
Then I have to mention: http://postgisonline.org
I have tried to build a way of trying spatial SQL queries online. There are a very few tutorials there: http://postgisonline.org/tutorials
anyone can write a tutorial and use it through the site. Look at http://postgisonline.org/doc There is still a lot to do with the site but there is not time enough. Anyone willing to contribute or give comments or ideas are very welcome.
Take a look at Portable GIS:
provide beginners with a ready-installed and configured stack of open source GIS tools that would run in windows without the need for emulation or a live cdemulation or a live cd
i.e. You can have it up and running on a USB stick. Very handy for workplace environments.
It has on it:
PostgreSQL (version 8.4)/Postgis (version 1.4)
A good start can be the PostGIS Manual edited by Paul Ramsey.
A course on spatial databases from Dublin Institute of Technology http://www.comp.dit.ie/pbrowne/Spatial%20Databases%20SDEV4005/Spatial%20Databases%20SDEV4005.htm
The PostGIS Wiki has list of tutorials as well. http://trac.osgeo.org/postgis/wiki/UsersWikiTutorials
Since this year (2014), we've got the excellent "PostGIS Cookbook" from Packt publishing [Paolo Corti, Stephen Vincent Mather, Thomas J Kraft, Bborie Park]
A lot of cases are explained with working instructions.
Try this book it's awesome
very clear, lot of examples.