I'm confused why one needs R or similar software to analyze complex data. Is there anything that can be done with R but not SQL?
For instance, I think R is used by biologists, http://www.genomebiology.com/2004/5/10/R80 can the same analysis be done with SQL?
What R brings to the table are numerous statistical methods packages and some good data visualization packages. With just a few lines you can apply some sophisticated techniques and produce beautiful visualizations.
SQL can indeed do some complex analytics, but they're very difficult, so R is the easier platform for statistics and machine learning. I did a Coursera class recently in which we had to do matrix multiplication with SQL and even that was a brain teaser of a puzzle. The advantages of doing analytics within a database are (a) leveraging the query optimizer to speed up your analysis and (b) you can make the analysis available to other users of the same system via a view or stored procedure, so they don't have to do the same work twice.