I'm an IT professional and I'm looking for institutions offering
distance learning courses to deepen my knowledge. I'm especially
interested in databases and datawarehouseing.

Dear Stephan, 

Here are several opportunties for you. 

Distance Learning Courses - DePaul University
<www.cs.depaul.edu/courses/distancelearning.asp> 
Data Warehousing and Data Mining
<http://www.cs.depaul.edu/programs/courses.asp?deptmne=IS&courseid=549> 

University of London External Programme
BSc and Diploma in Computing and Information Systems
<http://www.londonexternal.ac.uk/undergraduate/cis/index.shtml> 

e-Distance Learning Center 
<www.e-learningcenter.com> - offers courses on the subjects you're interested in. 

DeVry University 
<http://www.devry.edu/online/program_cis.html> 

I hope this answered your question. These are just some of the routes
you could take. You should decide what you need (degree, few courses,
etc.), at what costs and what sort of acknowledgement (or
accreditation) you need.

Search Strategy: 
searched distance learning programs for database or data warehousing programs.