PostGIS, which currently has a written version 1.5.2, is a spatial database extender for PostgreSQL Database Management System, which is used as a backend spatial database for geographic information systems (GIS), such as ESRI SDE or Oracle's Spatial extension. Unlike the two last-mentioned database servers, PostGIS is an open source GIS software under the GNU General Public License.
If you just want to start studying PostGIS, BostonGIS has made PostGIS and PostgreSQL tutorials on its website. For starters, maybe you could start with the Getting Started With PostGIS: An almost Idiot's Guide.
There is more guidance to learn the PostGIS on the site, please look at his homepage to find other tutorials PostGIS and PostgreSQL.
BostonGIS has also released a book PostGIS in Action in hardcopy and PDF format. I've posted previously about this book in May 2009. Now the book has many revisions, a more complete discussion and thicker, last updated in April 2011. PDF format of the book is actually a lot of "scattered" on the internet for download through file sharing sites
If you just want to start studying PostGIS, BostonGIS has made PostGIS and PostgreSQL tutorials on its website. For starters, maybe you could start with the Getting Started With PostGIS: An almost Idiot's Guide.
There is more guidance to learn the PostGIS on the site, please look at his homepage to find other tutorials PostGIS and PostgreSQL.
BostonGIS has also released a book PostGIS in Action in hardcopy and PDF format. I've posted previously about this book in May 2009. Now the book has many revisions, a more complete discussion and thicker, last updated in April 2011. PDF format of the book is actually a lot of "scattered" on the internet for download through file sharing sites